Suppose there are two guys, let's call them Tom and Joe, who walk into a room and find it empty, except there is a painting of the Eiffel Tower hanging on the wall. Tom says, "I wonder who painted that." Joe replies, "No one painted it." Tom asks, "How can you say that? Someone must have painted it." To which Joe replies, "I don't see an artist in the room. I've never personally met the one who painted it. I have never seen, heard, or touched the one who painted it. Therefore, no one must have painted it."
Ben, I think your approach to the question of a creator for the universe is much like Joe's approach to the question of who painted the picture of the Eiffel Tower. You say that because you have never seen any evidence for the creator of the universe, the universe must not have a creator. But I would say that, if the universe began to exist, then it had some sort of creator. And like the identity of the artist, we can learn a lot about whatever created the universe from the evidence within the universe itself. Like with the question of who made the painting of the Eiffel Tower, we could determine much about the artist's identity from the painting, even if he didn't sign his name at the bottom. We could guess that the artist was a good or bad painter, depending on the picture's quality. We could guess that the artist had probably been to France, and perhaps was French, or at the very least had seen a picture of the Eiffel Tower. We could also certainly assume that the artist was a human being as opposed to a cat or a zebra.
And since we are relatively certain that the universe began to exist at some point, we can determine much about the force that created it from the universe itself, even if we cannot see, hear, or touch this force. We can certainly determine that the force, if it created nature, is not a natural force itself. And since time is dependent on nature, we can determine that the force is a timeless one. Since there is much order within the natural laws, order which made life not only possible but apparently inevitable, we can determine that the force is intelligent and had a purpose.
You say that since God cannot be experienced using the five senses, God must not exist. I will assume you believe that there are many other planets outside of our solar system, but have you ever experienced these planets using your five senses? No? Then does that mean that you believe no planets exist outside our solar system? In this universe, there is much that exists that you have not experienced using your five senses. You say, "A transcendent God is by definition outside of all human universe, understanding, knowledge, and experience. We literally have no way of figuring out what this sort of creature is." That would be true if humans are purely material creatures, but we're not. It will perhaps be impossible for me to convince you of this, but we have spirits as well. And God, being a spiritual being, speaks to the spiritual part of us. The question is whether or not we're willing to listen. If one chooses to focus completely on the material part of himself, and ignore the spiritual part, then one is not only denying God, but a major part of himself.
You say that even if one could prove there is a cause for the universe, one could not prove that there is a God. I beg to differ. As I pointed out in my opening argument, if something created the universe, that in itself would tell us a lot about it. You say, 'There are many sorts of ideas of beings that could have created the universe.' Whatever the being was, it would have to have the qualities I outlined above, just as someone who made a painting of the Eiffel Tower would have to have specific qualities. If someone is going to claim that the creator of the universe is a natural being, or one subject to time, or a non-creative force, then such a claim would be wrong given the evidence at hand, just like if someone made the claim that the painting of the Eiffel Tower was made by a cat, or someone who had never seen even a picture of the Eiffel Tower.
You made the comment that the universe could have been created by blue fairies, just as easily as it could have been created by God. I have very little experience with blue fairies, so I don't know if they would fit the criteria necessary to have been the creators of the universe. Are they natural or supernatural beings? Are they timeless or not? Are they able to create matter from nothing, or not? I would say that being 'blue' as we know it suggests that they are natural beings, since the color blue exists only in the natural realm. To suppose that blue fairies do fit the criteria for the creator of the universe, and then to suppose that blue fairies DID create the universe, is like assuming that the painter of the Eiffel Tower painting is named 'Bob'. We could say it's possible, but we have no reason to suppose it's true. If there was some evidence that the painter was named 'Bob', then it would be logical to assume his name was 'Bob'. If we're supposing that the universe had a creator, I could give you reasons to suppose that the God of the Bible is this being. I have evidence, though you certainly have the right to refute the evidence, just as one could refute the evidence that the painter's name was 'Bob', if we had any.
Regarding the second law of Thermodynamics, I think you misunderstood how I was applying it to what we were talking about. You say that there is no order in our universe, but then also admit that we are a catalyst creating disorder. How can we be creating disorder, if order doesn't exist? What I'm saying, and science will back me up on this, that the universe itself is moving away from order towards disorder. If order does not exist, then the second law of Thermodynamics would be meaningless. If the universe always existed (and you seem to agree that it did not always exist), then there would not currently be an order-to-disorder progression occurring, since the process would have been completed by now. And if the universe began to exist at some point, then where did the order that we are moving away from, come from? It takes a lot of order for life to exist and be sustained on Earth. There are hundreds of natural laws working in unison to make sure that we continue to exist. I agree that gravity is helping to keep the sun together for the time being, but you will not find one scientist who will disagree that eventually the sun will burn itself out, which means that the sun is moving away from order towards disorder, despite the attempts by the law of gravity to salvage it.
You say, "You also keep referring to the natural world and alluding to a supernatural realm. And my central question to you is why do think this supernatural realm exists? The scientific evidence to which you refer is just not there." First off, we would not expect science to be able to prove the existence of a supernatural realm, since science deals only with the natural. As I believe I said earlier, to ask science to prove the existence of a supernatural realm is like asking someone to prove the existence of Bill Cosby using only mathematics. But if all that is natural began to exist, then something which is not natural had to have created it.
And by the way, I was surprised that you said I don't believe that there are atheists who have determined that there is no God due to having analyzed the evidence and using reason, since I consider you to be a part of this group, and practically said as much in my response to your opening argument. If I considered you to be a part of the first group you mentioned, those who simply don't want to believe in God, I would not be discussing this with you. And also, you suggested that I believe in God because of the Bible. Actually, I believed in God for many years before I even began looking at the Bible. In fact, most of those who believe in God do not believe in the Bible. Of the theists in the world, Jews and Christians make up less than half.
Besides, I said from the beginning of this argument that I didn't want to discuss whether the 'God of the Bible' is the God who created the universe, since discussing this is probably pointless unless we suppose that God exists. Let's deal with one subject at a time here. If you refuse to believe that the universe had a creator, there will be no point in arguing whether the God of the Bible is that creator.
I was struck by something you said at the very end of your letter, which was "the desire to believe is very similar to the desire not to believe, but neither has any merit when compared to the desire of truth." I completely agree with you that our primary obligation is to the truth. If God does not exist, we shouldn't believe that He does. If God does exist, we shouldn't believe that He doesn't. Many years ago, when I was an atheist, I decided that I really wanted to know whether or not God existed. I was comfortable in my belief that He didn't exist, but wasn't comfortable with the idea that maybe He did exist and I just didn't know it. I wanted to know the truth, whichever it happened to be. And, well, to make a long story short, here I am.