John Loftis, at his blog Debunking Christianity, lists ten objections, concepts, or topics that seem to be raised most often by atheists in debates with theists. Over the course of the next few days, I'd like to comment on them. Here's the third (my response to the earlier objections can be found by scrolling down the page):
3. There is a gap between natural theology and revealed theology. Arguing for a prime mover is not the same thing as arguing for any faith tradition.
This is true, but it's a mistake to think that natural theology leads us merely to a "prime mover." Without going into the arguments, we can say that the being arrived at by natural theology at the very least is the creator of the universe. This entails that this being would be unimaginably powerful, intelligent, and knowledgeable. It also entails that the being would transcend space, time and matter and also possess necessary existence.
Since causes are either personal or impersonal, and since we find that some of the effects of this cause have personality (us), it's not a stretch to think that the cause of personality must itself be personal. In fact, since natural theology concludes that this being is the ground of moral values and duties and is thus itself in some sense a moral being, and since only personal beings can be moral, we have good grounds for thinking the creator is personal.
Given the above, natural theology certainly leads us to an approximation of the theistic God if not to God Himself.
This, however, is a minimal description of the sort of being to which natural theology leads us. Many philosophers believe it's reasonable to conclude that God is a being which instantiates maximum greatness. If so, then that being is not just very powerful but powerful enough to do whatever is logically possible to do; not just very intelligent but omniscient; not just morally good but morally perfect, and so on. In other words, God possesses all great-making properties.
Of course, demonstrating via natural theology that God exists is not the same as demonstrating that Christianity is true, but it's a crucial step along the way. The truth of Christianity depends on the testimony of Scripture, but that testimony can only be credible to one who believes that God exists.