When I was writing about the Muslim apologetics, pretty much all the arguments kept coming back to the fine tuning argument. Basically, this argument says that if some fundamental parameters of the universe were different, the world wouldn't look the way it does and we would not exist in our current forms. Creationists extrapolate from that to the idea that therefore the parameters must have been specifically set that way by some intelligent, conscious entity in order to generate a universe that can house us. Then they generally then make a wild leap to assuming that this hypothesised intelligent, conscious entity still watches us, meddles in the world, wants a relationship with us and cares deeply about how and when we have sex.
But even the basic idea is flawed. It assumes that we are somehow special, that the universe was designed for life. We only have to look around to see that it isn't true. If you were randomly transported into any location in the Universe, there is more than a 99.9999999999999% chance that you will die. You'll probably land in empty space and die. But you could also land in or near a star and die. Or on the surface of a planet that is too hot or too cold and die. Or in or near a black hole and die. The Universe is deeply inhospitable to life. We only know of one place in the Universe that supports life, and it has been a difficult battle at times even here.
There are other arguments too. How do we know the life the Universe was designed for was us? Maybe the designer wanted dolphins? Or maybe the universe was actually designed for beings in some other galaxy and we just happened to pop up like an annoying bit of mold in the corner of the shower?
But to me, the answer is clearly the anthropic principle. The only universe in which we could be alive to observe that the parameters are compatible with life is one that necessarily must have parameters that are compatible with life! If they weren't, we would be here to notice. Nothing would.
I recently came across an excellent article that takes this one step further. If we just happened to evolve in this universe, we would expect to find that it has parameters compatible with life. It is just impossible for things to be any other way. But if an omnipotent deity created us and put us in this universe, there isn't necessarily a need to have fine tuned it for us. An omnipotent deity could presumably keep us alive even though the universe isn't set up to support life. If we observed that, it would be powerful evidence for some kind of entity supporting us. Go read the article - he does a much better job explaining it than I do :-)