Final answer:
The primary belief distinguishing the Jewish faith from other ancient religions is the worship of a single God (monotheism), specifically Yahweh, which was a marked deviation from the polytheistic practices of surrounding cultures.
Step-by-step explanation:
The main belief that distinguished the Jewish faith from others in the ancient world is A) the worship of a single god rather than many gods. This evolution from henotheism to a strict monotheistic worship transformed over time. Eventually, the Jews identified themselves with the exclusive worship of Yahweh, setting their religious practices apart from the polytheistic traditions common in the surrounding cultures.
In the framework of what we know today as Judaism, the Jewish people were expected to worship only Yahweh, follow the laws of Moses, and lead a moral life according to divine commandments. This unique relationship with a single deity, alongside the covenant that promised a mutual commitment between Yahweh and the Jewish people, is captured in their sacred texts such as the Torah and the interpretations found in the Talmud.
The monotheistic belief of Judaism that there is one true God, Yahweh, significantly contrasts with the polytheistic religions of the ancient world, where multiple deities were acknowledged and worshiped.