The ancients were not psychotic bullies who believed that you had to bribe or threaten people into loving the Gods. The Gods simply were and those who acknowledged them reaped the benefits of communion with the divine while those who didn’t deprived themselves of such blessings.
While the soul is judged after death in both Greek and Egyptian thought, with our good and evil deeds weighed in a balance, “belief” doesn’t really enter into the equation. There is punishment for our wickedness, but it is commensurate with our actions – not an excruciating torment from which there is no hope of escape.
Once we have atoned for our wrongdoing we either go on to our posthumous abode – Haides for most, the Isles of the Blest for a few or Tartaros for an even smaller number – or else, according to the Orphics and Pythagoreans at least, we are born again on earth in order to improve our future lot. But you have to be exceptionally evil to end up in Tartaros – Sisyphos, Tantalos, or Lykourgos level evil. Or in terms most will understand: Hitler, Dahmer or Phelps.