I've noticed that g3k, despite attributing all evil in the world to godless scientists, has not jumped into the discussion of how thousands of years of slavery was justified by (numerous and explicit) references to the Bible.
I suspect that even some evolutionists are uncomfortable with the notion that morality also evolves.
It should be expected. It's an adaptation, after all. One of the reasons I was upset over the banning of EsotericLudity many moons ago (a banning which eventually turned out to have been justified by his behavior on very different threads) was that I first saw the point below posted by him.
The Old Testament (Leviticus) expounds a nomadic, tribal morality. The New Testament lays out one more suitable for a sedentary, even urban one. It's much "softer," more "touchy-feely," because people are forced to interact much more with total strangers, not just family and extended family. The old laws had obviously become increasingly out of joint with the present-day realities. Pressures arise for new ways of getting along because things change.