As to the title of this piece - my feeling is that parents are primarily responsible for whether or not children accept religion. Without parents to consistently reinforce religious beliefs they would as jel implies go the way of Jack Frost, the Tooth Fairy, etc....

In response to LaurieB, I think most children certainly seem curious -- constantly asking why and all. Skeptical? Not always perhaps, but I know that the answer "because I said so" was never a very satisfying answer for me as a child when said by a parent. Similarly, "because the Bible says so" also failed to impress.

If memory serves it was often possible to gain my compliance (if not acceptance) with "because I said so" by adding "or your grounded" and/or "or you will get the belt". I was fortunate to never get any parental threats of punishment (in this life or any afterlife) for not participating in or believing in religion, however.

There may well be an nature component to it -- but I think how much and how long you hold on to religion is more of a "nurture" issue.