Andrew, my first question is what are the sources of truth? Another way of asking that is, "Is science the only true source of truth?"
I think that atheists put a lot of stock into scientific truth and argue that because God cannot be proved scientifically, then He cannot be proven at all. I think this is wrong for two reasons. First, science does not reach ultimate truth. Second, there are other sources of truth beyond science. Also, science ultimately points toward a Creator. So on one hand, I am arguing that science is not the end all of truth. On the other hand, I also argue that if one wants to rely on science, ultimately it points to God.
Society tends to view science as the ultimate search for truth, and that "scientific laws" are absolutely true. I am not so sure this is correct, however. For example, we used to think that atoms are the smallest, most basic elements that make up everything. Now science is telling us that atoms are comprised of strings, and that the elements that make up everything are some sort of harmonic string theory. The point is that there are few, if any, "laws" in science which will not be disposed of as science continues to investigate things. Our society lauds scientific truth, yet that truth is rarely absolute.
Also, science cannot speak to certain things. For example, it is true that a mother loves a child, yet it could not be proved scientifically. There may be evidence of love such as hugs and kisses, yet, science cannot measure the content of a person's heart. Science, therefore, is not the only source of truth. Recently, Stephen Hawking made headlines by essentially declaring that there was no heaven. Yet, science has nothing to say about the existence of heaven. There is no way to discover heaven through the scientific process. Thus, the atheist reliance on science to say that God does not exist is misplaced.
Finally, I would take issue with the one who says that we cannot prove God through the scientific method, therefore, He must not exist. I am not saying we can prove God through the scientific method. I am arguing, however, that science points toward a Creator. For example, I believe it is more rational to believe that God created the earth (perhaps through a Big Bang) than it is to believe that we came to exist through some primordial soup.
Are you willing to admit, then that science is not the only source of truth? Are you willing to admit that science points to a design and that, therefore, there must be a Designer?