Time magazine has an interview with Michael Coogan, editor of The New Oxford Annotated Bible and author of “God and Sex: What the Bible Really Says”:
There is no unequivocal statement in the Bible, especially the Hebrew Bible, that says that monogamy should be the norm. For the most part, biblical characters we know well, if they could afford it, had many wives. Solomon, the greatest lover of them all — maybe why he’s attributed with writing the Song of Songs — had 300 wives. So the fundamentalist Mormons who insist that polygamy is biblical are right, in a sense. If you’re going to be a strict literalist, there’s nothing wrong with polygamy.
Coogan says there’s much misunderstanding and that gets used by people to promote their philosophy and belief.