John: First, can the Mormon comparisons. Mormons for the most part avoid claiming that historical evidence supports Mormonism. Their apologetics consists of arguments to the effect that their religion isn't refuted by counterevidence, and that their beliefs are positively confirmed by one's own personal "testimony." What Mormons have been doing with the DNA claim has been to retreat from the historic Mormon position where contemporary Native Americans are identified as Lamanites, that is, descendants of people who were written about in the Book of Mormon. I think it slightly preposterous to suggest that the epistemic situation of Christianity is really no different from Mormonism.
I don't see anything in archaeology that suggests that the Exodus can be disproven in the same way that the historical Mormon claim that Native Americans are Lamanites has been disproven. At most, perhaps we don't have the confirmation we wish we had. It would be nice if you have the kind of archaeological confirmation for the whole Bible that you have for the second half of Acts of the Apostles (a confirmation that, of course, gets pooh-poohed whenever it is mentioned), but alas, we don't have anything that good for the Exodus. It is interesting how, when archaeology confirms the Bible, it is not important, but when archaeology fails to confirm the Bible, it's important. Heads I win....).
I would say that I do agree with the writer of this critique in that I think that you show a lack of discernment in perceiving wider implications for scientific discoveries. My favorite example was where you grabbed onto an ABC News article about the genetic basis for infidelity, and treated it like established science, not noticing that it's too early in the game to be making those sorts of pronouncements. As an example of someone, also an atheist and a practicing scientist, who is far better than you are at drawing careful implications from scientific developments, I would mention Blue Devil Knight.
Your mention of years of study is simply an appeal to your own authority, and for reasons I noted above, I am less than impressed. Going from science to broader implications involves two steps which have to be done carefully. First, you have to be sure that this is really good science, and you have to have a sense of how wide of support it has within the scientific community. Second, you have to be able to see how much real support the science actually provides to the claim you want to defend. Even fundamentalists insist that you have to exegete Bible passages if you want to use them. The same holds true, surely, for the Book of Science.