Hi Cold Steel,
Both Cofy and Qcmbr have commented on your current faith, which I assume is LDS (please correct me if I'm wrong). I've known one person who left Jehovah's Witnesses, became a Mormon, left that and is now an evangelical Christian. If you're using this forum as a safe-proxy to examine doubts you might have about Mormonism (perhaps even somewhat subconsciously) I have great sympathy for that, since I did exactly the same thing on the alt.religion.mormon Usenet group in the 1990s. If you had asked me at the time I would have not publically expressed any doubts my Witness faith, yet it facinated me how anyone could truly believe in Mormonism, when it has a so obviously flawed basis in the Book of Mormon.
I now believe my incredulity about why people believe was itself naive. Qcmbr I think hits upon some of the key reasons. The failed factual basis of a given faith is only one aspect, much larger is the wider cultural engagement. In terms of the failed facts, a simple read of a few right-sounding appologists and one can be comforted. But in the end there is no real basis to believe Babylon destroyed Jerusalem in 607 BCE (the real date in 587 BCE) and everyone outside the Witness faith is wrong. Likewise, there is no real basis to believe the history of pre-Columbus Americas involved ancient Jewish settlers of the Book of Mormon, and everyone outside the LDS faith is wrong.
Your OP opens the thread on how assumptions can be the basis for a faith, that seems to pop into existence with little else. Both Cofty & Qcmbr comments do make me wonder how other Ex-JWs and current Witnesses who have left yet, view Mormonism. I'll open a new thread on that.
Cheers,
-Randy