A silly argument keeps popping up whether one can be an atheist and still be a moral person. Well of course you can, I've seen it myself.
It's less silly at the next level, however. Does it work into the next generation? Can it hold for two generations? We have a hard time measuring this, because nearly every American was religion-affiliated in 1960, so there isn't a good control group for comparison. (Also, in terms of sexual morality, I think the cause flowed in the other direction, at least in my generation. People first decided or fell into having sex, then decided that their church rules were outmoded, and dropped the faith of their parents. The dissonance was too great. Philosophy did not undermine behavior; behavior undermined the philosophy.)
Still, a case could at least be made that the habits of a foundational morality give the false impression that morality can be sustained indefinitely without a religious faith. I bring it up because of the conflicts suddenly arising on the left between the Boomer liberals who adopted a fashionable skepticism and even nihilism, versus a younger PC crowd that was raised on relativism as a reality. The former were church-raised and deeply rooted in the western tradition. As the younger generation turns its skepticism on them (Jonathan Chait and Josh Marshall most recently) they have been aghast. Rather like Obama's horror that OWS was including his friends, and even he himself, in their protests. It was one of the few times we saw the inner conflict break out into a sweat on Barack's face. He thought he identified with them, and so thought they must identify with him. He moved heaven and earth for the PR on that one, even though it may have cost him with the general public. Shaken to the core.
One can hear it still in the religious assumptions the people of my generation still make even while professing to be Buddhists or other Eastern or alternative spiritualities. Their skin is no longer Christian, but their bones still are, though they know it not.
That is is now only half true for the next generation down, and simply no longer true at all for the liberals* in the generation after that; and it is not mere lack of Biblical knowledge that I reference here. A great deal of the western intellectual tradition persists, even as it is being mocked and rejected. But it is eroding, and those who thought no foundation is needed are no wondering what will come next.
*Plus a lot of the conservatives and independents.