A couple weeks ago in one of my seminary classes someone mentioned a "biblical model for marriage" during a class discussion. This ignited some fireworks amongst the students, but especially amongst the teachers (there are two teachers for this class: a main teacher and a co-teacher). In general, I think their sentiment could be summed up by saying they didn't think there was any evidence for a singular "biblical" model for marriage. The co-teacher said that the "biblical model for marriage" that she saw most prevalently in the Bible was one of polygamy. After all, it seems like everyone in the Old Testament had several wives. This doesn't seem to jibe with the modern Christian belief that marriage is between one man and one woman, so how do we explain that (it should be noted that she said this in somewhat of a flippant manner, to show how supposedly ridiculous it is to suggest that the Bible would actually insist on a particular model for marriage, and to ostracize those who would believe that they have discovered it)? The professor stated that "I can't find a biblical model of marriage that I can get excited about." His sentiment was based on the fact that pretty much every time you can see a marriage in the Bible, it's screwed up: David, Solomon, etc.
But I think this line of thinking is, to say the least, really uninformed, not to mention completely fallacious in its attempt to discount the idea that marriage is designed by God to be between one man and one woman, which, to be sure, was the intention of my teacher(s). Especially the bit about polygamy being the supposed biblical model for marriage. Just because polygamy existed - even amongst the Old Testament saints - does not mean that it was a God-ordained model for marriage. God did not give his "rubber stamp" of approval on those who had many wives. In fact, God said that having many wives would lead to sin and difficulty. So just because many, if not most, of the folks in the Old Testament had several wives, it doesn't mean that God condoned their actions. In fact, coupled with what Jesus says, it would seem that a lot of those OT saints were living in perpetual adultery. Just because people practiced polygamy didn't make it God's "design" for marriage, or even OK.
In Matthew 19 Jesus says that Moses allowed the Israelites to divorce their wives because they had hard hearts. In other words, because they were sinful - prideful, lustful, and selfish. Divorce was not God's ideal for marriage, and it still isn't. It was permitted by Moses, however, because the people were hard hearted. So, using my professor's line of thinking, is God OK with divorce because the Israelites practiced it? No. Does the fact that divorce took place in the Bible nullify an ideal biblical design for marriage? Certainly not. To suggest that it does would be ignorant.
I would argue the same for all deviations from what I believe is the God-ordained plan for marriage: one man and one woman, for as long as they both shall live. Anything other than this, while perhaps culturally acceptable (or is made acceptable by a hard-hearted generation) is not the ideal. This would mean that all of the Old Testament saints that had multiple wives were not following God's ideal design for marriage.
This gets interesting when we look to other cultures, however. In some cultures, women are completely dependent upon men for their livelihood. They won't eat or have anywhere to live unless they are married to a man who is able to provide for them. So, when a woman's husband dies, she may be forced to marry her dead husband's brother or some other relative just so she can survive. So in some cultures, polygamy can be used as a means of providing for the needy and showing compassion. Maybe this was part of the reasoning of the Old Testament saints, as well. I don't know.
But I think we can still say that this is not God's ideal for marriage. Yes, widows are being provided and cared for, and yes, it is a cultural system in which polygamy is used almost as a means of compassion. Does that mean it isn't sin? I don't know. God will judge that. But I believe it still stands that this is not what God intended.
When my professor said he couldn't find a biblical model of marriage that he could "get excited about," based on the screwed up marriages of people like David and Solomon, he similarly lacked perspective about marriage and the people involved in it. David didn't screw up his marriage because God's plan for marriage was flawed. David screwed up his marriage because David was a fallen, sinful human being. Solomon didn't take 700 wives and 300 concubines because God's plan for marriage wasn't good enough. Solomon took all those women because Solomon was selfish, prideful, and lustful. In every case where marriage doesn't "work," the problem is not the institution of marriage - it's the sinful, fallen people in the marriage. The fact that people in the Bible screwed up their marriages doesn't prove that God's design for marriage was/is wrong. It only proves that the people in the marriage were sinful people!
We need to also note that for all the ways that people can goof up or not follow God's design for marriage, there are an equal number of ways to bring about forgiveness and restoration to marriage and to the lives of the people involved. There is always hope. There is always the opportunity for repentance and forgiveness. And I would also argue that this is part of the genius of God's design for marriage. When people work through the difficulties in marriage in order to conform it more to what God desires for it, it shows the value of the institution.
I'm not claiming to be an expert on what the Bible says about marriage, and God knows that my own hard heart confounds his ideal for my own marriage. But what I do know for sure is that pointing to the polygamy of the Old Testament as proof that God does not have an ideal model for marriage, or that unsuccessful marriages show that God's design is flawed, are arguments that lack serious historical and biblical perspective.