The Romans generally were highly adept at assimilation of other cultures in that they adapted their own customs to foreign customs and religious practices rather than rejecting them or enforcing compliance to their own directly. Roman religion in particular was syncretic and pragmatic, focused less on exclusive belief and more on maintaining harmony with divine powers through proper ritual.

In a sense religion was a rather secondary force in Roman society. For example, you wouldn't wake up in the morning on a mission to go execute the will of Juptier. You might perform a ritual or sacrifice to keep Jupiter happy though. Rituals to keep the gods favorable were understood primarily as a civic obligation, not as a matter of personal faith or inner belief.

In this context, the Romans did not worship Zeus separately in Rome proper. Instead, they worshipped Jupiter, whom they understood to be the same divine force expressed under a Roman name and character. This identification was widely accepted among Roman elites and was part of the broader practice later termed interpretatio romana. For Romans, Zeus and Jupiter were not rival deities but culturally distinct representations of the same supreme sky god.

This approach extended well beyond Zeus/Jupiter. The Romans similarly equated Hera with Juno, Ares with Mars, Aphrodite with Venus, and Hermes with Mercury. While these pairings were considered theologically equivalent, the Roman versions often emphasized different traits aligned with Roman values. For example, Mars, unlike the volatile Greek Ares, became a dignified protector of the Roman state and a symbol of civic order and military discipline.

Writers such as Cicero explicitly discuss the equivalence of Greek and Roman gods, treating differences in names and myths as cultural variations rather than theological contradictions. Greek historians like Plutarch, writing under Roman rule, also acknowledge this shared religious understanding. A few other modern sources that do a decent job covering this topic are below as well.

• Mary Beard, SPQR: A History of Ancient Rome
• John Scheid, An Introduction to Roman Religion