I like this argument...
"There are at least 2 objective, yet certain ways to know God exists. The first is through his Creation. Imagine finding a new, hi-tech watch in a forest. There would be no doubt in your mind that it was created, though you have never seen anything like it before. Thanks to the electron microscope, we now know that a single living human cell is FAR more complex than the most modern factory. Creation of life, now is obvious - especially to experts in biochemistry. This necessitates a Creator (God). But you donít need a degree in molecular biology or quantum physics. The Bible says Creation by God has been obvious since the beginning of time... that we are "without excuse" [Rom 1:20]."