There are accounts in the Bible that involve men having multiple wives. There are also groups in this day and age that believe Christians should practice polygamy. Since men in Biblical times tended to have more than one wife, does this mean that this is God’s plan for us today? This could easily be compared to the question of slavery. It’s mentioned in the Bible, and God allowed it. Does that mean that God necessarily condoned it? No!
Going back to Genesis (2:18-25) marriage is instituted between Adam and Eve. If polygamy had been God’s plan, certainly God could have created multiple women for Adam. Jesus restates this understanding of a monogamous marriage when questioned. (Mark 10:5-8) Male Christian leaders in the New Testament are to have one wife (1 Timothy 3:1-3, 11-13; Titus 1:5-7)
Throughout the history of Christianity, monogamy has been the norm. The first time polygamy was widely practiced by a group claiming Christian beliefs was in the early history of Mormonism (Latter-Day Saints). The LDS discontinued and forbade polygamy in 1890, although breakaway Mormon groups do practice polygamy. Modern polygamy among groups professing Biblical forms of Christianity is rare.
In the Bible, polygamy has had its share of problems (the rivalry between Rachel and Leah comes to mind, as well as the problems with King Solomon taking numerous wives). It’s possible that the Biblical model for marriage was planned so that the problems associated with polygamy would be avoided.
Rather than a God-instituted family model, it seems that polygamy was permitted by God for cultural reasons in a time when most women were dependent on men for both safety and finances. This is why I don’t believe polygamy should be upheld as a model for all time.