Until modern times the relationship of morals to religion was taken
for granted, and writers as far different in philosophy as Plato and
Avicenna, or in theology as Aquinas and Luther, never questioned the
basic truth expressed on Mt. Sinai when Yahweh gave the Jews the
decalogue whose first precepts were to honor God as a foundation for
the secondary precepts of the moral law.

But something new has entered the stream of human thought, the
concept of man's autonomy that wishes to dispense with religion in
its bearing on morals, on the grounds that the very notion of
religious values is only a mental construct. Whatever bearing they
may have on ethical principles, it is not as though the concept of
God was a necessary conation for being moral in the current, accepted
sense of the term.

Where the fifth century monk Pelagius denied the existence of grace
because he felt this encouraged lazy dependence on supernatural aid,
latter day critics of religion would remove the existence of God for
the same reason except that their Pelagianism is more complete,
perhaps because their confidence in Man is so extreme.