Judaism

The term Judaism derives from Iudaismus, a Latinized form of the Ancient Greek Ioudaismos (Koine Greek: Ἰουδαϊσμός, from the verb ἰουδαΐζειν 'to side with or imitate the [Judeans]'). Its ultimate source is the biblical "Yehudah" (יהוּדָה, Yəhūda), the Hebrew name for Judah, son of Jacob, and the namesake of the tribe of Judah, the region of Judah, and the Kingdom of Judah. The term Ioudaismos first appears in the Koine Greek book of 2 Maccabees in the 2nd century BCE (specifically 2 Maccabees 2:21, 8:1 and 14:38). In the context of the age and period, it meant "seeking or forming part of a cultural entity". It resembled its antonym Hellenismos, a word signifying submission to Hellenistic cultural norms. The conflict between Ioudaismos and Hellenismos lay behind the Maccabean Revolt; hence, the term Ioudaismos.

Rabbi Shaye J. D. Cohen writes in his book The Beginnings of Jewishness:

We are tempted, of course, to translate [Ioudaïsmós] as "Judaism," but this translation is too narrow, because in this first occurrence of the term, Ioudaïsmós has not yet been reduced to the designation of a religion. It means rather "the aggregate of all those characteristics that makes Judaeans Judaean (or Jews Jewish)." Among these characteristics, to be sure, are practices and beliefs that we would today call "religious," but these practices and beliefs are not the sole content of the term. Thus Ioudaïsmós should be translated not as "Judaism" but as Judaeanness.

Daniel R. Schwartz, however, argues that "Judaism", especially in the context of the books of the Maccabees, refers to the religion, not the culture and politics of the Judean state. He believes it reflected the ideological divide between the Pharisees and Sadducees and, implicitly, anti-Hasmonean and pro-Hasmonean factions in Judean society.

According to the Oxford English Dictionary, the earliest citation of the term in English was in Robert Fabyan's 1516 book The New Chronicles of England and France, in which "Judaism" is described as "the profession or practice of the Jewish religion; the religious system or polity of the Jews". "Judaism" as a direct translation of the Latin Iudaismus first appears in a Christian 1611 English translation of 2 Maccabees 2:21: "Those that behaved themselves manfully to their honour for Iudaisme."

A large portion of the Hebrew Bible recounts the Hebrews' relationship with God from their earliest traditions through the Second Temple period (i.e., until roughly 70 CE, when the Temple was destroyed). Abraham, initially called Abram (אַבְרָם, Avram), is presented as the ancestor of the Israelites, the descendants of Jacob—whose name is changed to Israel (יִשְׂרָאֵל, Yīsrāʾēl) in Genesis 32:29—and thus the Hebrews. In the patriarchal age, God establishes a covenant with Abraham that includes the institution of circumcision (בְּרִית מִילָה, brit milah, 'covenant of circumcision') as a sign of that covenant, established when Abraham was 99 years old; the requirement to circumcise the males of his household is recorded in Genesis 17:10–14. God changes Abram's name to Abraham in Genesis 17:5 and Sarai's (שָׂרָי) name to Sarah (שָׂרָה). Sarah is promised to bear a son in her old age, and that son, Isaac (יִצְחָק, Yīṣḥāq), will be the child of the covenant and Abraham's heir, whose descendants will inherit the land often called Canaan.

In the book of Exodus, the second book of the Hebrew Bible, the descendants of Isaac's son Jacob were enslaved in Egypt during a period of harsh oppression. God, appearing to Moses in a divine vision through a burning bush on Mount Horeb, commands him to lead the Hebrews out of bondage. God inflicts ten plagues upon Egypt—such as the Nile turning to blood, swarms of locusts, and the death of the firstborn—to persuade Pharaoh to release the Hebrews. After the final plague, Pharaoh relents, and the Hebrews begin their escape, known as the Exodus. They travel across the desert and arrive at Mount Sinai, where God bestows the commandments, laws, and teachings that will define the moral and spiritual foundation of the Israelite community, as recounted in the subsequent chapters. These books, together with the Nevi'im and Ketuvim, are known as Written Torah, as opposed to the Oral Torah, which refers to the Mishnah, Talmud, and halakhic Midrashim (מִדְרָשִׁים, 'expositions'; sing. Midrash). The Nevi'im consist of historical narratives and prophetic writings, focusing on the Israelites' settlements in Canaan. The Ketuvim, a diverse collection of books including the book of Psalms, book of Proverbs, and book of Esther, covers poetic and prose philosophical writings that deviate from the more literalist style of the other books.

Rabbinic tradition holds that the details and interpretation of the Oral Torah were originally unwritten traditions based on the Law given to Moses at Sinai. However, as the persecution of Jews increased in intensity and frequency and the details of the Oral Torah were in danger of being forgotten, Judah ha-Nasi compiled them into the Mishnah, which was redacted c. 200 CE. The Talmud is a compilation of the Mishnah and Gemara, rabbinic commentaries redacted over the next three centuries. The Gemara originated in two major centers of Jewish scholarship: Palestine and Babylonia (Lower Mesopotamia). Correspondingly, two bodies of analysis developed, and two compilations of the Talmud were created. The older compilation is called the Jerusalem Talmud. It was compiled sometime during the 4th century in Palestine.

According to the Hebrew Bible, the United Kingdom of Israel was established under Saul the King and continued under King David and Solomon, with its capital being Jerusalem. After Solomon's reign, the nation split into two kingdoms, the Kingdom of Israel in the north and the Kingdom of Judah in the south. The Kingdom of Israel was destroyed around 720 BCE, when it was conquered by the Neo-Assyrian Empire; many people were taken captive from the capital Samaria to Media and the Khabur River valley. The Kingdom of Judah continued as an independent state until it was conquered by Nebuchadnezzar II of the Neo-Babylonian Empire in 586–87 BCE.

The Babylonians destroyed Jerusalem and the First Temple, forcing the Israelites into the Babylonian captivity in what is regarded as the first Jewish diaspora. Many of the Israelites returned to their homeland—an event known as the return to Zion—after the fall of Babylon was accomplished by the Persian Achaemenid Empire seventy years later. The Second Temple was constructed, and religious practices were resumed.

During the early years of the Second Temple, the highest religious authority was the Great Assembly, led by Ezra. Among other accomplishments of the Great Assembly, the last books of the Hebrew Bible were written at this time and the canon was sealed. Hellenistic Judaism spread to Ptolemaic Egypt from the 3rd century BCE, and its creation sparked widespread controversy in Jewish communities, starting "conflicts within Jewish communities about accommodating the cultures of occupying powers." Later, during the First Jewish–Roman War (66–73 CE), the Romans sacked Jerusalem and destroyed the Second Temple.

Later, Roman emperor Hadrian built a pagan idol on the Temple Mount and prohibited circumcision. These acts of ethnocide provoked the Bar Kokhba revolt (132–136 CE), after which the Romans banned Torah study and the celebration of Jewish holidays and forcibly removed virtually all Jews from Judea. In 200 CE, however, Jews were granted Roman citizenship and Judaism was recognized as a religio licita (lit. 'licit religion' or 'legitimate religion') until the rise of Gnosticism and early Christianity in the fourth century.

Following the destruction of Jerusalem and the expulsion of the Jews, Jewish worship stopped being centrally organized around the Temple; prayer took the place of sacrifice; worship was conducted within the Jewish communities of the diaspora; and the authority of Chazal (pronounced [χaˈzal]; חֲזַ״ל, a Hebrew acronym for חֲכָמֵינוּ זִכְרוֹנָם לִבְרָכָה, Ḥakhaméinu zikhronam livrakhah, 'our Sages, of blessed memory') and rabbis who acted as teachers and leaders of individual communities was established.

Judaism in pre-Islamic Arabia goes back to the pre-Christian period, and was concentrated in the northwest and south. In the fourth century, the ruling class of the Himyarite Kingdom of pre-Islamic South Arabia converted to Judaism. This situation lasted until the early sixth century, when the Aksumite invasion of Himyar, instigated by the massacre of Najran, led to a transition to Christian domination.

Unlike other ancient Near Eastern gods, the Jewish God is portrayed as unitary and solitary; consequently, the Jewish God's principal relationships are not with other gods, but with the world, and more specifically, with the people he created. Judaism thus begins with ethical monotheism: the belief that God is one (הַשֵּׁם אֶחָד, haššēm ʾeḥād, 'HaShem [is] one'), reflected by religious Jews' twice-daily recitation of Shema Yisrael (שְׁמַע יִשְׂרָאֵל ה׳ אֱלֹקֵינוּ ה׳ אֶחָד, šəmaʿ yiśrāʾēl YHWH ʾĕlōhê-nû YHWH ʾeḥād, 'Listen, Yisra'el: HaShem [is] our God; HaShem [is] one'), and concerned with the actions of humankind. According to the Hebrew Bible, God promised Abraham that he would make of his offspring a great nation. Many generations later, he commanded the Israelites to love and worship only one God; that is, the Jewish nation is to reciprocate God's concern for the world. He also commanded the Jewish people to love one another; that is, Jews are to imitate God's love for people.

Thus, although there is an esoteric tradition in Judaism in Kabbalah, Conservative rabbi and scholar Max Kadushin has characterized normative Judaism as "normal mysticism", because it involves everyday personal experiences of God through ways or modes that are common to all Jews. This is played out through the observance of Halakha and given verbal expression in the Birkhot Ha-Mitzvot (בִּרְכוֹת הַמּצְווֹת, 'Blessings [of] the Mitzvot'), the short blessings recited every time a positive commandment is to be fulfilled:

The ordinary, familiar, everyday things and occurrences we have, constitute occasions for the experience of God. Such things as one's daily sustenance, the very day itself, are felt as manifestations of God's loving-kindness, calling for the Berakhot. Kedushah, holiness, which is nothing else than the imitation of God, is concerned with daily conduct, with being gracious and merciful, with keeping oneself from defilement by idolatry, adultery, and the shedding of blood. The Birkat Ha-Mitzwot evokes the consciousness of holiness at a rabbinic rite, but the objects employed in the majority of these rites are non-holy and of general character, while the several holy objects are non-theurgic. And not only do ordinary things and occurrences bring with them the experience of God. Everything that happens to a man evokes that experience, evil as well as good, for a Berakhah is said also at evil tidings. Hence, although the experience of God is like none other, the occasions for experiencing Him, for having a consciousness of Him, are manifold, even if we consider only those that call for Berakot.

Whereas Jewish philosophers often debate whether God is immanent or transcendent, and whether people have free will or their lives are determined, Halakha is a system through which Jews act to recognize God in the world. Ethical monotheism is central in all sacred or normative texts of Judaism. However, monotheism has not always been followed in practice. The Hebrew Bible records and repeatedly condemns the widespread worship of other gods in ancient Israel. In the Greco-Roman era, many different interpretations of monotheism existed in Judaism, including the interpretations that gave rise to Christianity.

Moreover, some have argued that Judaism is a non-creedal religion that does not require one to believe in God. For some, observance of Halakha is more important than belief in God per se. The debate about whether one can speak of authentic or normative Judaism is not only a debate among religious Jews but also among historians.

Judaism does not possess fixed, universally binding articles of faith, in the same sense as those instituted by Christianity and Islam, though some are incorporated into the liturgy to a certain extent. Scholars throughout Jewish history have proposed numerous formulations of Judaism's core tenets, all of which have met with criticism. In the 12th century, Maimonides developed his 13 principles of faith, which is the most widely accepted formulation. According to Maimonides, any Jew who rejects even one of these principles would be considered an apostate and a heretic. Jewish scholars have held points of view diverging in various ways from his principles. Thus, within Reform Judaism, only the first five principles are endorsed.

In the time of Maimonides, his list of tenets was criticized by Hasdai Crescas and Joseph Albo. Albo and Abraham ben David argued that his principles contained too many items that, while true, were not fundamentals of the faith. Along these lines, the ancient Jewish historian Josephus emphasized practice and observances rather than theology, associating apostasy with a failure to observe Halakha and maintaining that the requirements for conversion to Judaism included circumcision and adherence to traditional customs. The 13 principles were largely ignored over the next few centuries. Later, two poetic restatements of these principles, Ani Ma'amin (אֲנִי מַאֲמִין, ʾănî maʾămîn, 'I believe') and Yigdal (יִגְדַּל, 'may [God] be magnified'), became integrated into many Jewish liturgies, leading to their eventual near-universal acceptance.

The oldest instance of the Karaite movement's formulation of articles of faith is found in the work of the 12th-century figure Judah Hadassi:

God is the Creator of all created beings;

He is premundane and has no peer or associate;

The whole universe is created;

God called Moses and the other Prophets of the Biblical canon;

The Law of Moses alone is true;

To know the language of the Bible is a religious duty;

The Temple at Jerusalem is the palace of the world's Ruler;

Belief in Resurrection contemporaneous with the advent of the Messiah;

Final judgment;

Retribution.

In modern times, Judaism lacks a centralized authority that dictates orthodoxies. Because of this, many variations on basic beliefs are considered within the scope of Judaism. Even so, all Jewish religious movements are, to a greater or lesser extent, based on the principles of the Hebrew Bible and various commentaries, including the Talmud and Midrash. Judaism also universally recognizes the biblical covenant between God and the patriarch Abraham, as well as the additional aspects of the covenant revealed to Moses, who is considered Judaism's greatest prophet. In the Mishnah, a core text of Rabbinic Judaism, acceptance of the divine origins of this covenant is considered an essential aspect of Judaism, and those who reject the covenant forfeit their share in the world to come.

Establishing the core tenets of Judaism in the modern era is even more challenging, given the numerous and diverse contemporary Jewish religious movements. Even if restricting the problem to the most influential intellectual trends of the nineteenth and twentieth centuries, the matter remains complicated. Thus, for instance, Rav Joseph B. Soloveitchik's (associated with Modern Orthodox Judaism) answer to modernity is constituted upon the identification of Judaism with following the Halakha, whereas its ultimate goal is to bring holiness down to the world. Rabbi Mordecai Kaplan, the originator of Reconstructionist Judaism, abandons the idea of religion for the sake of identifying Judaism as a civilization, and by means of the latter term and secular translation of the core ideas, he tries to embrace as many Jewish movements as possible. In turn, Solomon Schechter's Conservative Judaism was identical with the tradition understood as the interpretation of Torah, in itself being the history of the creative interpretation and reinterpretation of the Hebrew Bible and Halakha. Finally, David Philipson draws the outlines of the Reform movement by opposing it to the strict and traditional rabbinical approach and thus comes to conclusions somewhat similar to that of the Conservative movement.

The following is a basic, structured list of the central works of Jewish practice and thought:

The Tanakh (תַּנַ״ךְ, tanaḵ), its translations, and its primary exegeses:

The Tanakh itself:

The Torah (תּוֹרָה, Tôrâ, lit. 'Instruction' or 'Teaching')

The Nevi'im (נְבִיאִים, Nĕbîʾîm, 'Prophets')

The Ketuvim (כְּתוּבִים, Kĕtûvîm, 'Writings')

The Masorah (מָסוֹרָה, 'tradition')

Targumim (תַּרְגּוּמִים, 'translations')

Jewish biblical exegesis (also see Midrash below)

Primarily legal works of the Talmudic era (i.e., classical rabbinic literature)

The Mishnah (מִשְׁנָה) and its commentaries

The Tosefta (תוֹסֶפְתָּא, 'supplement') and the minor tractates

The Talmuds:

The Babylonian Talmud (תַּלְמוּד בַּבְלִי, Talmûd Bāblî) and its commentaries

The Jerusalem Talmud (תַּלְמוּד יְרוּשַׁלְמִי, Talmûd Yerûšalmî; also known as תַּלְמוּד אֶרֶץ יִשְׂרָאֵל, Talmûd ʾEreṣ Yiśrāʾēl, 'Talmud [of the] Land [of] Israel') and its commentaries

Midrash (מִדְרָשׁ, 'textual interpretation'):

Midrash Halakha (מִדְרַשׁ הֲלָכָה)

Midrash Aggadah (מִדְרַשׁ אַגָּדָה)

Halakha (הֲלָכָה, Halākhāh, 'Jewish law'):

Codes of Jewish law and custom, such as:

Maimonides's Mishneh Torah (מִשְׁנֵה תּוֹרָה, Mišnê Tôrâ, 'Repetition [of the] Torah') and its commentaries

Rabbi Jacob ben Asher's Arba'ah Turim (אַרְבָּעָה טוּרִים, ʾArbāʿāh Ṭurîm, 'Four Rows'), as well as its commentaries

Rabbi Joseph Karo's Shulchan Aruch (שֻׁלְחָן עָרוּךְ, Šulḥān ʿĀrûḵ, 'Set Table') and its commentaries

The responsa literature

Other components of Jewish thought:

Works of Jewish philosophy, such as those of Jewish existentialism and Holocaust theology

Musar (מוּסָר, Mûsār, 'ethics') and other works on Jewish ethics and conduct

Kabbalah (קַבָּלָה, Qabbālāh, 'Reception')and other streams of Jewish mysticism

Works of Hasidic philosophy (חֲסִידוּת, Ḥasidût, lit. 'piety' or 'devoutness'), the foundation of Hasidic Judaism

Jewish prayer books, which vary across Jewish religious movements:

Siddurim (סִדּוּרִים; sing., סִדּוּר, siddûr, 'order [of prayers]'), which are used throughout most of the Jewish religious calendar

Machzorim (מַחְזוֹרִים, Maḥzôrîm; sing., מַחְזוֹר, maḥzôr, lit. 'cycle' or 'recurrence'), which are used only during the High Holy Days

Other works on the Jewish liturgy, including piyyutim (פִּיּוּטִים, piyyûṭîm, 'liturgical poems'; sing., פִּיּוּט, piyyûṭ)

The basis of halakha and tradition is the Torah (also known as the Pentateuch or the Five Books of Moses). According to rabbinic tradition, there are 613 commandments in the Torah. Some of these laws are directed only to men or to women, some only to the ancient priestly groups, the Kohanim and Leviyim (members of the tribe of Levi), some only to farmers within the Land of Israel. Many laws were only applicable when the Temple in Jerusalem existed, and only 369 of these commandments are still applicable today.

While there have been Jewish groups whose beliefs and practices were based on the written text of the Torah alone (e.g., the Sadducees, and the Karaites), most Jews follow the oral law. These oral traditions were transmitted by the Pharisee school of thought in ancient Judaism and later recorded in writing and expanded upon by the rabbis.

According to Rabbinical Jewish tradition, God gave both the Written Law (the Torah) and the Oral Torah to Moses on Mount Sinai. The Oral law is the oral tradition as relayed by God to Moses and from him, transmitted and taught to the sages (rabbinic leaders) of each subsequent generation.

For centuries, the Torah existed only as a written text transmitted alongside the oral tradition. Fearing that the oral teachings might be forgotten, Rabbi Judah haNasi undertook the mission of consolidating the various opinions into one body of law which became known as the Mishnah.

The Mishnah consists of 63 tractates that codify halakha, the basis of the Talmud. According to Abraham ben David, the Mishnah was compiled by Rabbi Judah haNasi after the destruction of Jerusalem, in anno mundi 3949, which corresponds to 189 CE.

Over the next four centuries, the Mishnah was discussed and debated in both the world's major Jewish communities (in Israel and Babylonia). The commentaries from each of these communities were eventually compiled into the two Talmuds, the Jerusalem Talmud (Talmud Yerushalmi) and the Babylonian Talmud (Talmud Bavli). These have been further expounded upon by the commentaries of various Torah scholars throughout the ages.

In the text of the Torah, many words are left undefined, and many procedures are mentioned without explanation or instructions. Such phenomena are sometimes offered to support the view that the Written Law has always been transmitted alongside a parallel oral tradition, thereby suggesting that the reader is already familiar with the details from other, i.e., oral, sources.

Halakha, the rabbinic Jewish way of life, is then based on a combined reading of the Torah and the oral tradition—the Mishnah, the halakhic Midrash, the Talmud, and its commentaries. The halakha has developed slowly, through a precedent-based system. The literature of questions to rabbis, and their considered answers, is referred to as responsa (Hebrew Sheelot U-Teshuvot). Over time, as practices develop, codes of halakha are written that are based on the responsa; the most important code, the Shulchan Aruch, largely determines Orthodox religious practice today.

Jewish philosophy refers to the conjunction between serious study of philosophy and Jewish theology. Major Jewish philosophers include Philo of Alexandria, Solomon ibn Gabirol, Saadia Gaon, Judah Halevi, Maimonides, and Gersonides. Major changes occurred in response to the Enlightenment (late 18th to early 19th century), leading to the emergence of post-Enlightenment Jewish philosophers. Modern Jewish philosophy encompasses both Orthodox and non-Orthodox perspectives. Notable among Orthodox Jewish philosophers are Eliyahu Eliezer Dessler, Joseph B. Soloveitchik, and Yitzchok Hutner. Well-known non-Orthodox Jewish philosophers include Martin Buber, Franz Rosenzweig, Mordecai Kaplan, Abraham Joshua Heschel, Will Herberg, and Emmanuel Lévinas.

Orthodox and many other Jews do not believe that the revealed Torah consists solely of its written contents, but of its interpretations as well. The study of Torah (in its widest sense, including both poetry, narrative, and law, and both the Hebrew Bible and the Talmud) is, in Judaism, itself a sacred act of central importance. For the sages of the Mishnah and Talmud, and for their successors today, the study of Torah was therefore not merely a means to learn the contents of God's revelation, but an end in itself. According to the Talmud:

These are the things for which a person enjoys the dividends in this world while the principal remains for the person to enjoy in the world to come; they are: honoring parents, loving deeds of kindness, and making peace between one person and another. But the study of the Torah is equal to them all. (Talmud Shabbat 127a).

In Judaism, "the study of Torah can be a means of experiencing God". Reflecting on the contribution of the Amoraim and Tanaim to contemporary Judaism, Professor Jacob Neusner observed:

The rabbi's logical and rational inquiry is not mere logic-chopping. It is a most serious and substantive effort to locate in trivialities the fundamental principles of the revealed will of God to guide and sanctify the most specific and concrete actions in the workaday world. ... Here is the mystery of Talmudic Judaism: the alien and remote conviction that the intellect is an instrument not of unbelief and desacralization but of sanctification.

To study the Written Torah and the Oral Torah in light of each other is thus also to study how to study the word of God.

In the study of Torah, the sages formulated and followed various logical and hermeneutical principles. According to David Stern, all Rabbinic hermeneutics rest on two basic axioms:

first, the belief in the omni-significance of Scripture, in the meaningfulness of its every word, letter, even (according to one famous report) scribal flourish; second, the claim of the essential unity of Scripture as the expression of the single divine will.

These two principles make possible a great variety of interpretations. According to the Talmud:

A single verse has several meanings, but no two verses hold the same meaning. It was taught in the school of R. Ishmael: 'Behold, My word is like fire—declares the Lord—and like a hammer that shatters rock' (Jer 23:29). Just as this hammer produces many sparks (when it strikes the rock), so a single verse has several meanings." (Talmud Sanhedrin 34a).

Observant Jews thus view the Torah as dynamic, because it contains within it a host of interpretations.

According to Rabbinic tradition, all valid interpretations of the written Torah were revealed to Moses at Sinai in oral form and handed down from teacher to pupil (the oral revelation is, in effect, coextensive with the Talmud itself). When different rabbis forwarded conflicting interpretations, they sometimes appealed to hermeneutic principles to legitimize their arguments; some rabbis claim that these principles were themselves revealed by God to Moses at Sinai.

Thus, Hillel called attention to seven commonly used hermeneutical principles in the interpretation of laws (baraita at the beginning of Sifra); R. Ishmael, thirteen (baraita at the beginning of Sifra; this collection is largely an amplification of that of Hillel). Eliezer b. Jose ha-Gelili listed 32, largely used for the exegesis of narrative elements of Torah. All the hermeneutic rules scattered through the Talmudim and Midrashim have been collected by Malbim in Ayyelet ha-Shachar, the introduction to his commentary on the Sifra. Nevertheless, R. Ishmael's 13 principles are perhaps the ones most widely known; they constitute an important, and one of Judaism's earliest, contributions to logic, hermeneutics, and jurisprudence. Judah Hadassi incorporated Ishmael's principles into Karaite Judaism in the 12th century. Today, R. Ishmael's 13 principles are incorporated into the Jewish prayer book to be read by observant Jews daily.

According to Daniel Boyarin, the underlying distinction between religion and ethnicity is foreign to Judaism itself, and is one form of the dualism between spirit and flesh that has its origin in Platonic philosophy and that permeated Hellenistic Judaism. Consequently, in his view, Judaism does not fit easily into conventional Western categories, such as religion, ethnicity, or culture. Boyarin suggests that this in part reflects the fact that much of Judaism's more than 3,000-year history predates the rise of Western culture and occurred outside the West (that is, Europe, particularly medieval and modern Europe). During this time, Jews experienced slavery, anarchic and theocratic self-government, conquest, occupation, and exile. In the Jewish diaspora, they were in contact with, and influenced by, ancient Egyptian, Babylonian, Persian, and Hellenic cultures, as well as modern movements such as the Enlightenment (see Haskalah) and the rise of nationalism, which would bear fruit in the form of a Jewish state in their ancient homeland, the Land of Israel. Thus, Boyarin has argued that "Jewishness disrupts the very categories of identity, because it is not national, not genealogical, not religious, but all of these, in dialectical tension."

In contrast to this point of view, practices such as Humanistic Judaism reject the religious aspects of Judaism, while retaining certain cultural traditions.

According to Rabbinic Judaism, a Jew is anyone who was either born of a Jewish mother or who converted to Judaism in accordance with halakha. Reconstructionist Judaism and the larger denominations of worldwide Progressive Judaism (also known as Liberal or Reform Judaism) accept the child as Jewish if one of the parents is Jewish, if the parents raise the child with a Jewish identity, but not the smaller regional branches. All mainstream forms of Judaism today are open to sincere converts, although conversion has traditionally been discouraged since the time of the Talmud. The conversion process is evaluated by an authority, and the convert is examined on his or her sincerity and knowledge. Converts are called "ben Abraham" or "bat Abraham", (son or daughter of Abraham). Conversions have on occasion been overturned. In 2008, Israel's highest religious court invalidated the conversion of 40,000 Jews, mostly from Russian immigrant families, even though they had been approved by an Orthodox rabbi.

Rabbinical Judaism maintains that a Jew, whether by birth or conversion, is a Jew forever. Thus a Jew who claims to be an atheist or converts to another religion is still considered by traditional Judaism to be Jewish. According to some sources, the Reform movement has maintained that a Jew who has converted to another religion is no longer a Jew, and the Israeli Government has also taken that stance after Supreme Court cases and statutes. However, the Reform movement has indicated that this is not so cut and dried, and different situations call for consideration and differing actions. For example, Jews who have converted under duress may be permitted to return to Judaism "without any action on their part but their desire to rejoin the Jewish community" and "A proselyte who has become an apostate remains, nevertheless, a Jew".

Karaite Judaism believes that Jewish identity can only be transmitted by patrilineal descent. Although a minority of modern Karaites believe that Jewish identity requires that both parents be Jewish, and not only the father. They argue that only patrilineal descent can transmit Jewish identity on the grounds that all descent in the Torah went according to the male line.

The question of what determines Jewish identity in the State of Israel was given new impetus when, in the 1950s, David Ben-Gurion requested opinions on mihu Yehudi ("Who is a Jew") from Jewish religious authorities and intellectuals worldwide to settle citizenship questions. This is still not settled, and occasionally resurfaces in Israeli politics.

Historical definitions of Jewish identity have traditionally been based on halakhic definitions of matrilineal descent, and halakhic conversions. Historical definitions of who is a Jew date back to the codification of the Oral Torah into the Babylonian Talmud, around 200 CE. Interpretations of sections of the Tanakh, such as Deuteronomy 7:1–5, by Jewish sages, are used as a warning against intermarriage between Jews and Canaanites because "[the non-Jewish husband] will cause your child to turn away from Me and they will worship the gods (i.e., idols) of others." Leviticus 24 says that the son in a marriage between a Hebrew woman and an Egyptian man is "of the community of Israel." This is complemented by Ezra 10, where Israelites returning from Babylon vow to put aside their gentile wives and their children. A popular theory is that the rape of Jewish women in captivity brought about the law of Jewish identity being inherited through the maternal line, although scholars challenge this theory citing the Talmudic establishment of the law from the pre-exile period. Since the anti-religious Haskalah movement of the late 18th and 19th centuries, halakhic interpretations of Jewish identity have been challenged.

The total number of Jews worldwide is difficult to assess because the definition of "who is a Jew" is problematic; not all Jews identify themselves as Jewish, and some who identify as Jewish are not considered so by other Jews. According to the Jewish Year Book (1901), the global Jewish population in 1900 was around 11 million. The latest available data is from the World Jewish Population Survey of 2002 and the Jewish Year Calendar (2005). In 2002, according to the Jewish Population Survey, there were 13.3 million Jews around the world. The Jewish Year Calendar cites 14.6 million. It is 0.25% of world population.

Jewish population growth is currently near zero percent, with 0.3% growth from 2000 to 2001. The overall growth rate of Jews in Israel is 1.7% annually, and is consistently growing through natural population growth and extensive immigration. The diaspora countries, by contrast, have low Jewish birth rates, an increasingly elderly age composition, high rates of interreligious marriage and a negative balance of people leaving Judaism versus those joining.

In 2022, the world Jewish population was estimated at 15.2 million, with the majority living in one of two countries: Israel and the United States. About 46.6% of all Jews resided in Israel (6.9 million) and another 6 million Jews resided in the United States, with most of the remainder living in Europe, and other groups spread throughout Canada, Latin America, Asia, Africa, and Australia.

Jewish demographics represent diverse historical and cultural trajectories. Ashkenazi Jews, Sephardic Jews, Ethiopian Jews (Beta Israel), Mizrahi Jews, and Romaniote Jews, may possess unique customs and practices.

In Israel, the classification of Jewish observance into categories like Haredi, Dati, Masorti, and Hiloni was developed by sociologists and researchers studying the religious and cultural landscape of Israeli society. These distinctions emerged from surveys and studies conducted by the Israel Central Bureau of Statistics and scholars such as Shmuel Sandler, who explored how religious practices varied among different segments of the Jewish population. The categories were created to better understand the range of religious adherence, from the ultra-Orthodox Haredim to the secular Hilonim, with Dati and Masorti representing intermediary groups.

According to Pew Research Center (2020), about 85% of the global Jewish population of 14,780,000 is concentrated in two countries: Israel and the United States, which are the only nations with Jewish populations exceeding one million. Jews constitute 0.2% of the world's population. Outside these two primary countries, the nations with the largest Jewish populations, in descending order, are France, Canada, the United Kingdom, Argentina, and Russia. Even though Jewish birth rates are similar to the global average, the overall population has grown more slowly because it is older on average. By 2010, about one in three Jews worldwide was aged 50 or above, giving Jews the largest proportion of older adults among major religious groups.

Jewish communities are highly concentrated geographically: 96% live in the ten countries with the largest Jewish populations, totaling 14.2 million people. About 500,000 Jews live elsewhere in the world. Today, roughly 27,000 Jews reside in Muslim-majority countries, mainly in Turkey (14,200), Iran (9,100), and Azerbaijan (5,000). In the Arab world, the biggest Jewish populations are found in Morocco (2,000), Tunisia (1,000), and the United Arab Emirates (500).

Regionally, the Jewish population increased in the Middle East and North Africa (up 18% to nearly 7 million), and grew slightly in Asia-Pacific (2%) and North America (1%). It declined in sub-Saharan Africa (down 37% to 50,000), Latin America–Caribbean (down 12% to 390,000), and Europe (down 8% to 1.3 million). Despite these shifts, Jews remained a small and generally stable share of regional populations.