Like other major religions, Judaism is based on a number of beliefs, however it is not necessary to adhere to these beliefs to be Jewish. In Judaism, a person's behavior is as important as his beliefs. Maimonides explained the Jewish faith as the widely accepted "thirteen principles of faith". The famous Jewish philosopher Maimonides, who lived in the twelfth century and is known to Muslims as Ibn Maimun, is known as Rambam among Jews.
Maimonides sees the "thirteen principles of faith" as the minimum conditions of the Jewish faith:
Principle 1
God exists; God is perfect in every way, eternal, and the cause of all that exists. All other beings depend upon God for their existence.
Principle 2
God has absolute and unparalleled unity.
Principle 3
God is incorporeal–without a body.
Principle 4
God existed prior to all else. (In a later version of the Thirteen Principles, Maimonides included the notion that God created the world from nothing [creation ex nihilo].)
Principle 5
God should be the only object of worship and praise. One should not appeal to intermediaries, but should pray directly to God.
Principle 6
Prophets and prophecy exist.
Principle 7
Moses was the greatest prophet who ever lived. No prophet who lived or will live could comprehend God more than Moses.
Principle 8
The Torah is from heaven. The Torah we have today is the Torah that God gave to Moses at Sinai.
Principle 9
The Torah will never be abrogated, nothing will be added to it or subtracted from it; God will never give another Law.
Principle 10
God knows the actions of humans and is not neglectful of them.
Principle 11
God rewards those who obey the commands of the Torah and punishes those who violate its prohibitions.
Principle 12
The days of the Messiah will come.
Principle 13
The dead will be resurrected.
Just as these basic principles have been discussed one by one over time, many of them have also been discussed within the liberal movements of Judaism.
Unlike other religions, Judaism is not focused on abstract universal concepts. Although the Jews have thought deeply about issues such as God, man, the universe, life and afterlife, there is no mandatory, official, definitive idea about them other than the general concepts mentioned above. These issues, which are open to personal interpretation, are discussed among Jewish clergy today as in ancient times.
Judaism focuses on relationships: relationships between God and people, and relationships between people. Sacred texts describe the development of these relations, starting from the creation of the universe, the beginning of the relations between God and Abraham, the relations between God and the Jewish nation and their continuation. The Torah also explains the mutual obligations that come with these relationships, which different Jewish schools interpret differently.
