The probability that you don't understand cosmology is much higher than the probability that God exists. :-)

I came to Less Wrong as a firm atheist, but realized that I did not seem to have any personal basis for this belief. After I read this article, I decided to take a serious look at possibilities for a deity.

Funny. I came to LessWrong as a firm atheist, then realized that atheism was an answer to a question nobody ever had any rational right to ask.

Therefore, to the best of my knowledge science has no rational explanation for the amount of matter in this universe.

In other words, "science doesn't know how X happened, therefore god did it." This is the classic argument from ignorance. Much better to say "I don't know why matter predominates." That is a perfectly legitimate answer, even in the unlikely event that NO scientific explanation is ever forthcoming.

Obviously, the Bayesian probability for this is very weak, but it is also the only theory that I see that has any chance of being true, so it is one that I, as a rationalist should believe in.

There are a few things that are confused here. First of all, if this explanation is the only one you can think of, that does not mean you should believe in it.

If I watch a magic trick and I can't figure out how it was done, the only 'explanation' I can think of is magic. That does not mean it is rational to believe it was magic until I think of a better explanation. I just admit my confusion and keep thinking. :)

I do not expect this theory to last, or even be true, but it has the highest probability of being correct.

Actually, what "highest probability of being correct" MEANS is precisely that you should expect this theory to be true.

I do not expect this theory to last, or even be true, but it has the highest probability of being correct.

Quoth Anna: "If you can predict what you'll believe a few years from now, consider believing that already." If you have evidence that future evidence will require you to adjust your belief in a particular direction, then according to the laws of probability theory, you have evidence on which you're failing to update your current belief.

Anyway, aside from that in particular, you're pretty confused about several things, and I'm wondering if you've read "A Technical Explanation of Technical Explanation" and the sequences "Mysterious Answers to Mysterious Questions" and "Reductionism".

Apparently, there are causal/physical explanations for everything that occurs. It seems terribly unlikely that this feature of reality would suddenly break down at "matter and antimatter". To put it another way, the part of me that believes in God believes God would leave a nice explanation for physicists to discover for the asymmetry of matter and anti-matter as well as everything else. I guess I don't consider that question basic enough. The basic question, for me, is why there is anything at all - not just 'matter', but the rules and structure of the universe.

I think it's safe to say that CP violation and baryogenesis are just not very well-understood right now. Where are you getting this claim that there are "two possible explanations, one which results in too much matter and the other too little"? I find it very unlikely that this is exhaustive of what current theories people may have of baryogenesis, much less which ones are possible (and still far more probable than baryogenesis via gods).

Most of the matter in the universe, we have not observed. Most of the matter we have observed, we have done so only through its interaction with photons, which interact with matter and antimatter in the same way.

Are you sure this thing you are trying to explain actually happened?