What standards do believers have for making a Biblical case? Reading the Bible only reinforces my impression that the Bible can be used to justify many different (and contradicting) theological opinions.
A friend of mine once said that if there was even one verse in the Bible that supported a position, then that was sufficient support for that position. But by that standard, you could justify nearly anything. Certainly, as I pointed out to my friend, if one verse makes a sufficient case, then you could easily amass enough verses to make a very strong case for slavery. You can also justify contradicting positions until the cows come home. (A particularly annoying subset of these easy justifiers are those who argue that if you disagree with their type of Christianity, you are no better than a pagan.)
Other people go to the opposite extreme and say nothing but the most general themes can be taken from the Bible. If something is not a theme throughout the whole thing (or, at least, throughout the whole NT, for Christians), then it cannot be taken as an absolute. This, in some ways, is the more honest position, but it rather leaves a lot on the floor.
So I ask the believers, what are your standards for making a Biblical case that a certain belief is consistent with the Bible? Fellow non-Christians, feel free to comment upon what standards you would and would not think reasonable for a believer to a accept a belief based on Biblical justification.