One of the past week's most interesting religious stories was the announcement by atheist blogger Leah Libresco that she was planning to enter the Catholic Church. One of the many reports can be read here. The story is an interesting read. It seems that Libresco first became convinced of the reality of the moral order (or the natural law). If the moral order is really real, and not just part of our imagination, or a fluke of our evolutionary development, it does finally imply the existence of a God, because law (as in moral law) implies a lawgiver.
As an assignment for a seminary apologetics class, I moved an atheist friend of mine from his conviction of the reality of morality to acknowledgment of God through a series of logical steps. But I convinced his head, not his heart, and he ended up rejected the conclusion even while admitting the validity of the steps that led to it.
It's interesting to trace Libresco's movement along the same path, a path that tends toward Catholicism, which has the best articulated moral theology within the Christian tradition.