Christianity is rooted in Second Temple Judaism, but the two religions diverged in the first centuries of the Christian Era. Christianity emphasizes correct belief (or orthodoxy), focusing on the New Covenant as mediated through Jesus Christ, as recorded in the New Testament. Judaism places emphasis on right conduct (or orthopraxy), focusing on the Mosaic Covenant, as recorded in the Torah and Talmud.
Christians believe in individual salvation from sin through repentance and receiving Jesus Christ as their God and Savior through Faith in Christianity. Jews believe in individual and collective participation in an eternal dialogue with God through tradition, rituals, prayers and ethical actions. Christianity generally believes in a Triune God, one person of whom became human. Judaism emphasizes the Oneness of God and rejects the Christian concept of God in human form.
Traditionally, both Judaism and Christianity believe in the God of Abraham, Isaac, and Jacob, for Jews the God of the Tanakh, for Christians the God of the Old Testament, the creator of the universe. Judaism and major sects of Christianity reject the view that God is entirely immanent (although some see this as the concept of the Holy Ghost) and within the world as a physical presence, (although trinitarian Christians believe in the incarnation of God). Both religions reject the view that God is entirely transcendent, and thus separate from the world, as the pre-Christian Greek Unknown God. Both religions reject atheism on one hand and polytheism on the other.
Both religions agree that God shares both transcendent and immanent qualities. How these religions resolve this issue is where the religions differ. Christianity posits that God exists as a Trinity; in this view, God exists as three distinct persons who share a single divine essence, or substance. In those three there is one, and in that one there are three; the one God is indivisible, while the three persons are distinct and unconfused, God the Father, God the Son, and God the Holy Spirit. It teaches that God became especially immanent in physical form through the Incarnation of God the Son who was born as Jesus of Nazareth, who is believed to be at once fully God and fully human.
There are denominations self-describing as Christian who question one or more of these doctrines, however, see Nontrinitarianism. By contrast, Judaism sees God as a single entity and views trinitarianism as both incomprehensible and a violation of the Bible’s teaching that God is one. It rejects the notion that Jesus or any other object or living being could be ‘God’, that God could have a literal ‘son’ in physical form or is divisible in any way, or that God could be made to be joined to the material world in such fashion. Although Judaism provides Jews with a word to label God’s transcendence (Ein Sof, without end) and immanence (Shekhinah, in-dwelling), these are merely human words to describe two ways of experiencing God; God is one and indivisible.
In Judaism, God is understood to be the absolute one, indivisible, and incomparable being who is the ultimate cause of all existence. Judaism holds that YHWH, the god of Abraham, Isaac, and Jacob and the national god of the Israelites, delivered the Israelites from slavery in Egypt, and gave them the Law of Moses at biblical Mount Sinai as described in the Torah. Traditional interpretations of Judaism generally emphasize that God is personal, while some modern interpretations of Judaism emphasize that God is a force or ideal.
The name of God used most often in the Hebrew Bible is the Tetragrammaton (YHWH Hebrew: יהוה). In Jewish tradition, other names of God are Elohim and El Shaddai.
God in Christianity is the eternal being who created and preserves all things. Christians believe God to be both transcendent (wholly independent of, and removed from, the material universe) and immanent (involved in the world). Christian teachings of the immanence and involvement of God and his love for humanity exclude the belief that God is of the same substance as the created universe but accept that God’s divine Nature was hypostatically united to human nature in the person of Jesus Christ, in an event known as the Incarnation.
Rabbinic Judaism recognizes the 24 books of the Masoretic Text, commonly called the Tanakh or Hebrew Bible, as authoritative. Modern scholarship suggests that the most recently written are the books of Jonah, Lamentations, and Daniel, all of which may have been composed as late as the second century BCE.
The Book of Deuteronomy includes a prohibition against adding or subtracting, which might apply to the book itself (i.e. a “closed book”, a prohibition against future scribal editing) or to the instruction received by Moses on Mt. Sinai.
The book of 2 Maccabees, itself not a part of the Jewish canon, describes Nehemiah (around 400 BCE) as having “founded a library and collected books about the kings and prophets, and the writings of David, and letters of kings about votive offerings” (2:13–15). The Book of Nehemiah suggests that the priest-scribe Ezra brought the Torah back from Babylon to Jerusalem and the Second Temple (8–9) around the same time period. Both 1 and 2 Maccabees suggest that Judas Maccabeus (around 167 BCE) also collected sacred books (3:42–50, 2:13–15, 15:6–9).
There is no scholarly consensus as to when the Hebrew Bible canon was fixed: some scholars argue that it was fixed by the Hasmonean dynasty (140–40 BCE), while others argue it was not fixed until the second century CE or even later. The Catholic Pontifical Biblical Commission says that “the more restricted Hebrew canon is later than the formation of the New Testament”.
The Christian biblical canons are the books Christians regard as divinely inspired and which constitute a Christian Bible. Which books constituted the Christian biblical canons of both the Old and New Testament was generally established by the 5th century, despite some scholarly disagreements, for the ancient undivided Church (the Catholic and Eastern Orthodox traditions, before the East-West Schism).
In the wake of the Protestant Reformation, the Catholic canon was reaffirmed by the Catholic Church at the Council of Trent (1546), which provided “the first infallible and effectually promulgated pronouncement on the Canon” by the Roman Catholic Church. The canons of the Church of England and English Calvinists were decided definitively by the Thirty-Nine Articles (1563) and the Westminster Confession of Faith (1647), respectively. The Synod of Jerusalem (1672) established additional canons that are widely accepted throughout the Orthodox Church.
The Old and New Testament canons did not develop independently of each other and most primary sources for the canon specify both Old and New Testament books. A comprehensive table of biblical scripture for both Testaments, with regard to canonical acceptance in Christendom’s various major traditions, can be found here.