Dogma in Medieval Jewish Thought
Saadiah articulated Jewish creeds, Maimonides followed suit, and a group of 15th-century Spaniards continued the tradition.
Both early Islam and [the medieval sectarian movement] Karaite Judaism adopted the tools of Greek philosophy and logic, which defined belief (in Greek, pistis) in explicitly propositional terms. Such religious movements could not be ignored by the Judaism of that era, and in their attempt to expound and defend Judaism in this context, medieval Jewish thinkers began to conceive of the nature of belief in propositional terms.
It is hardly surprising, therefore, that the first systematic exposition of Jewish beliefs was undertaken by Saadiah Gaon, in light of his exposure to the latest currents of Moslem thought in tenth‑century Baghdad and his involvement in the struggle against Karaism.
Once the term belief was defined in terms of specific propositions to be accepted or rejected, as opposed to an attitude of trust and reliance upon God and acceptance of his Torah, it was only a question of time until an attempt would be made to codify in creedal fashion the most important beliefs of Judaism. That two hundred years were still to elapse between the provocations of Saadiah's day and the enterprise of Maimonides is a tribute to the conservative nature of the Jewish tradition.
That Maimonides undertook the project at all is a tribute to his boldness.
In 1168 Maimonides completed his first major work, the commentary on the Mishnah. In the course of this work Maimonides commented on Mishnah Sanhedrin 10:1, which reads as follows:
"All Israelites have a share in the world to come, as it is written, 'Thy people also shall be all righteous, they shall inherit the land forever; the branch of my planting, the work of my hands, wherein I glory' (Isaiah 60:21). But the following do not have a share in the world to come: he who says that resurrection is not taught in the Torah, he who says that the Torah was not divinely revealed, and the epikoros…"
By way of interpreting this text, Maimonides composed a lengthy essay in which, among other things, he defines the various terms occurring in the mishnah under discussion. It was apparently by way of defining the term Israelites in this mishnah that Maimonides listed those thirteen beliefs that, in his estimation, every Jew qua Jew had to accept.
These beliefs, known as the Thirteen Principles, may be summarized as follows: (1) that God exists; (2) that God is one; (3) that God is incorporeal; (4) that God is ontologically prior to the world; (5) that God alone is a fit object of worship; (6) that prophecy occurs; (7) that the prophecy of Moses is superior to that of all other prophets; (8) that the Torah was revealed from heaven; (9) that the Torah will never be uprooted or altered; (10) that God knows the acts of human beings; (11) that God rewards the righteous and punishes the wicked; (12) that the Messiah will come; and (13) that the dead will be resurrected.