Salon.com has an interview of Daniel Dennett who describes himself as a "bright", a person with "a naturalist as opposed to a supernaturalist world view." In his new book, Breaking the Spell: Religion as a Natural Phenomenon, Dennett argues for an examination of "religion as a product of evolution rather than a transcendental force."
If society doesn't get its moral foundation from religion, where will that foundation come from? What will keep us being good to each other, if not rules laid down by God?
Rules that we lay down ourselves. We've been doing this for centuries. There've been revisions about what counts as a sin in God's eyes. It has changed quite a bit since the days of the Old Testament. It has changed because people thought about it hard and could no longer stomach some of the old rules and practices and changed their minds. It became politically obvious that something had to give, and so it has, and will continue to do so. Now we can continue to expand the circle and get more people involved, and do it in a less disingenuous way by excising the myth about how this is God's law. It is our law.
Caution: The interview can be read for free after getting a "site pass", but you have to agree to view an ad. But, do get the site pass; the interview is worth the trouble.