No one knows whether the Romans really believed in their gods. I doubt they believed that their Emperors were really transformed into gods on death. In a book by Daniel J. Gargola called “The shape of the Roman order: the Republic and its spaces”, the author points out that they believed deeply in the rites of religion, the attempt to discern the will of the gods, expiate ill omens, and discern whether a public act was within the bounds of divine law. Religious rites had to be performed with precision. Auguries were taken in templa, and the buildings they were taken in had to be in precisely the right place with the right geographical orientation.

Epicurus was quite definite: there may be gods, but they live on Mt. Olympus, bicker and chase one another around the mountain, but have no time for the pathetic concerns of Man.
He never, as far as I know, commented on the rites of religion, and we do not know what he thought of the Roman preoccupation with auguries and so on because he wasn’t there But most emerging societies had these rites and superstitions, including the Greeks. I do believe he would have, had he been there, laughed at them and called them “lorem ipsum asynartisies” which, loosely translated, means “mumbo jumbo”. The flight of birds, the neighing of a horse at dawn, or the direction a tortoise walks when released – all these are totally random, and nothing useful can be deduced from them. But they are sufficiently obscure, and the people sufficiently ignorant, that they do allow priests to use them to exert power over their flocks and frighten them into obedience. Sometimes that obedience is a positive thing, if it produces a kind, thoughtful, considerate and cooperative population. More often it is just about power.