For the belief in the gods has not been established by authority, custom or law, but rests on the unanimous and abiding consensus of mankind; their existence is therefore a necessary inference, since we possess an instinctive or rather an innate concept of them; but a belief which all men by nature share and must necessarily be true; therefore it must be admitted that the gods exist. And since this truth is almost universally accepted not only among philosophers but also among the unlearned, we must admit it also being an accepted truth that we posses a ‘preconception,’ as I called it above, or ‘prior notion,’ of the gods.

Cicero, De Natura Deorum