We talked about a thorny issue in my seminary missions class today. What would you do if a new convert on the field was married to multiple wives? Do you tell him to divorce all but the first one or maintain the status quo? Or is there another option?
My initial instinct was that only the first marriage was biblically valid because God created marriage to be one man and one woman; therefore, subsequent marriages were not actual marriages in God's eyes and divorce would be appropriate and not really divorce at all. Then it occurred to me that the OT seems to recognize polygamous marriages as genuine marriages even if they arose outside God's intent, so perhaps the marriages should remain intact.
If that's not tough enough, the answer and the reasoning also has implications for how we address the problem of homosexual marriage. If we do concede that polygamous marriages can be valid in God's eyes even if they are outside His creative intent, then how can we use the argument that "marriage is one man and one woman" to repudiate homosexual marriage? Both polygamous marriages and homosexual marriages are contrary to this divine intent, but we cannot use that argument to say homosexual marriages are invalid if we concede that polygamous marriages are valid (but wrong).
Of course, that does not mean that there is no other way to make the case that homosexual marriage is invalid, but it does take away a common argument. I don't have the answers, so as Ross Perot used to say, "I'm all ears."