What do Jews believe in?
Judaism, like other major religions, has a set of beliefs, but one does not have to adhere to them to be a Jew. In Judaism, actions are as important as beliefs.
The closest that anyone has ever come to creating a widely-accepted list of Jewish beliefs is Maimonides, who formulated thirteen principles of faith.
Maimonides, known to Muslims as Ibn Maimun, was a renowned Jewish philosopher in the twelfth century.
Jews call him Rambam.
The thirteen principles of faith, which Maimonides thought were the minimum requirements of Jewish belief, are:
1. God exists
2. God is one and unique
3. God is incorporeal
4. God is eternal
5. Prayer is to be directed to God alone and to no other
6. The words of the prophets are true
7. Moses' prophecies are true, and Moses was the greatest of the prophets
8. The Written Torah and Oral Torah (teachings now contained in the Talmud and other writings) were given to Moses
9. There will be no other Torah
10. God knows the thoughts and deeds of men
11. God will reward the good and punish the wicked
12. The Messiah will come
13. The dead will be resurrected
As basic as these principles are, the necessity of believing each one of these has been disputed at one time or another, and the liberal movements of Judaism dispute many of these principles.
Unlike many other religions, Judaism does not focus much on abstract cosmological concepts. Although Jews have certainly considered the nature of God, man, the universe, life and the afterlife at great length, there is no mandated, official, definitive belief on these subjects, outside of the very general concepts discussed above. There is substantial room for personal opinion on all of these matters. Indeed, learned Rabbis (Jewish theologians) have been discussing these issues since ancient times and continue to do so today.
Judaism focuses on relationships: the relationship between God and mankind, between God and the Jewish people, and between human beings. Our scriptures tell the story of the development of these relationships, from the time of creation, through the creation of the relationship between God and Abraham, to the creation of the relationship between God and the Jewish people, and forward. The scriptures also specify the mutual obligations created by these relationships, although various movements of Judaism disagree about the nature of these obligations. Some say they are absolute, unchanging laws from God (Orthodox); some say they are laws from God that change and evolve over time (Conservative); some say that they are guidelines that you can choose whether or not to follow (Reform, Reconstructionist).