I take offense to any implications about my posterior.

Heck, even I upvoted this. Your point is well made, and well taken; even if archaeological evidence corroborates parts of the Book of Mormon, that does not update its probability to 1. I should have been more clear... no, rather, I should have thought of it that rationally, but I was blinded by my own certainty. I apologize; thank you for showing me my error.

Were I to rewrite the above, it would take the form of something like this:

The Book consists of two pieces of information: data that are archaeologically verifiable, and data that are not archaeologically verifiable. If archaeological evidences corroborate the Book's story, then there are two possibilities: either the non-archaeologically-verifiable bits are also true, or they are not. If the former is the case, then Joseph Smith's story is correct, the Church is true, etc. etc. If the non-archaeologically-verifiable bits are not true, given that the a.v. bits are, then we must conclude one of two things: either a coincidence (which probability becomes smaller with each additional corroborating evidence), or something Stranger, e.g. alien teenagers. I am inclined, given the current state of the evidence, to believe the above scenarios in the following order, in descending order of probability: a) The Book Is True, b) Aliens Are Trolling Us, c) Magnificent Coincidence. I also think that these three possibilities, and their subgroups, comprise the entirety of the probability space, but please correct me if there's a possibility I have overlooked.

Oh, as an aside: The proposition that "The mainstream LDS church is not true, but the truth is had by one of the handful of splinter groups that split off from the LDS church and still believe in the Book of Mormon" does in fact fall under possibility a, though considering the legal troubles surrounding some of these groups, this seems rather unlikely to me. After all, Joseph Smith published this as one of our thirteen Articles of Faith: "We believe in being subject to kings, presidents, rulers, and magistrates; in obeying, honoring, and sustaining the law."