Because those events are so real that they cast their shadow forward and backwards through all time, whenever men think of these matters at all. Even if they are mired in ignorace, they will see...fragments of the Truth, as men imprisoned in a cave see shadows cast by the sun. Likewise, all men derive their moral intuitions from God; how not? There is no other source, just as there is no other way to make a wheel than to make it round.
S.M. Stirling