“Modern people, even those who happen to be religiously observant, struggle to appreciate what it means for an entire society to inhabit world which is pervaded by invisible supernatural forces and populated by gods and spirits; and in which the very fabric of time and space is marked and divided by sacred places and rituals. There is another reason too for the gap in comprehension.
Ancient paganism amounted to a way of being religious which in crucial ways does not fit with Christian assumptions; and those assumptions have to a large extent passed unchallenged into the post-Christian worldview, colouring the very essence of what we might perceive religion to be.
Classical paganism was first and foremost a religion of tradition. Its practices and beliefs were handed down from generation to generation like to many cultural heirlooms. The individual did not practise their religion primarily because they were persuaded in their mind that its metaphysical claims were true, but because their parents and ancestors had done so since time immemorial. The emphasis was on performing the prescribed sacrifices and attending the customary festivals rather than on being taught from a catechism or believing in a creed. As the early modern French intellectual Bernard de Fontenelle put it, the rule was: 'Do what the others do, and believe what you wish'.
Put another way, Graeco-Roman paganism was a religion, but it was not a confession, in the sense of a collection of dogmas requiring intellectual agreement or self-conscious assent. Belief formed part of ancient religion in the trivial sense that the ancient Greek and Romans believed (probably, in most cases) that the gods to whom they performed rituals existed. But they did not believe, as Christians and Muslims later did, that correct religious belief was essential to their eternal spiritual destiny, or that the content of their beliefs needed to be strictly orthodox." They had a 'noncompulsory theology, over which not a single religious war was ever fought.”
Paganism Persisting : A History of European Paganisms Since Antiquity
Robin Douglas & Francis Young