In the course of a thought-provoking article, Glen Tinder writes:

The idealism of the man-god does not, of course, bring as an immediate and obvious consequence a collapse into unrestrained nihilism. We all know many people who do not believe in God and yet are decent and admirable. Western societies, as highly secularized as they are, retain many humane features. Not even tacitly has our sole governing maxim become the one Dostoevsky thought was bound to follow the denial of the God-man: “Everything is permitted.”

This may be, however, because customs and habits formed during Christian ages keep people from professing and acting on such a maxim even though it would be logical for them to do so. If that is the case, our position is precarious, for good customs and habits need spiritual grounds, and if those are lacking, they will gradually, or perhaps suddenly in some crisis, crumble.

To what extent are we now living on moral savings accumulated over many centuries but no longer being replenished? To what extent are those savings already severely depleted? Again and again we are told by advertisers, counselors, and other purveyors of popular wisdom that we have a right to buy the things we want and to live as we please. We should be prudent and farsighted, perhaps (although even those modest virtues are not greatly emphasized), but we are subject ultimately to no standard but self-interest.

Glenn Tinder, 1989. Can We Be Good Without God? The Atlantic Monthly, pp.69–85.  Emphasis added.