Religion of ancient Babylonia. Babylonian religion is usually referred to as Babylonian and Assyrian religion, as there are few changes between the Babylonians and the Assyrians in concepts and organization. There are still a few differences, then mainly in which gods were favoured. In Babylonian religion, the most prominent god was Marduk, who was not revered by the Assyrians. The Babylonians also had a strong concept relating to the god of the dead, Nergal.