As for the Book of Mormon... try to think of it this way. Imagine that, tomorrow, you meet aliens from a faraway star system. The aliens look like giant jellyfish, and are in fact aquatic; needless to say, they grew up in a culture radically different from ours. While this alien species does possess science and technology (or else they wouldn't make it all the way to Earth !), they have no concept of "religion". They do, however, have a concept of fiction (as well as non-fiction, of course, or else they wouldn't have developed science). The aliens have studied our radio transmissions, translated our language, and downloaded a copy of the entire Web; this was easy for them since their computers are much more powerful than ours. So, the aliens have access to all of our literature, movies, and other media; but they have a tough time making sense of some of it. For example, they are pretty sure that the Oracle SQL Manual is non-fiction (they pirated a copy of Oracle, and it worked). They are also pretty sure that Little Red Riding Hood is fiction (they checked, and they're pretty sure that wolves can't talk). But what about a film like Lawrence of Arabia ? Is that fiction ? The aliens aren't sure. One of the aliens comes to you, waving a copy of The Book of Mormon (or whichever scripture you believe in) in its tentacles (but in a friendly kind of way). It asks you to clarify: is this book fiction, or non-fiction ? If it contains both fictional and non-fictional passages, which are which ? Right now, the alien is leaning toward "fiction" (it checked, and snakes can't talk), but, with us humans, one can never be sure. What do you tell the alien ?

So this is a problem. In general, there are types of claims that don't easily have shared evidence (e.g. last night I had a dream that was really cool, but I forgot it almost as soon as I woke up, I love my girlfriend, when I was about 6 years old I got the idea of aliens who could only see invisible things but not visible things, etc.) But most claims, especially claims about what we expect of reality around us should depend on evidence that can be shared. [...] So this is already a serious mistake. One shouldn't try to find rational arguments in favor of one thing or another. One should find the best evidence for and against a claim, and then judge the claim based on that. [...] You may want to seriously consider that the arguments you are looking for don't exist. In the meantime, may I recommend reddit's Debate Religion forum. They are dedicated to discussing a lot of these issues and may be a better forum for some of the things you are interested. Of course, the vast majority of things related to rationality has very little to do with whether or not there are any deities, and so you are more than welcome to stick around here. There's a lot of interesting stuff going on here.