On the mission field, I live in a polygamous (okay, technically a polygynous) society where it is fairly common for men to have more than one wife. While this is largely because Niger is almost entirely Muslim and Islam permits each man to have up to 4 wives, historically most African cultures have practiced polygamy. Perhaps that partially explains why it was so easy for many Africans who practiced traditional faiths to peacefully convert to Islam, as little in family life needed to change with the new faith.
A few years ago, most Westerners probably couldn’t fathom what a polygamous household might be like. Then along came the cable series “Big Love” (which is popular on Middle East satellite stations) about a Mormon from one of their splinter sects who keeps three wives in three adjacent houses. I can't say that I'm a fan of the series, but it does provide some fascinating insights into a polygamous lifestyle and it seems to capture some of the issues that are faced by polygamous homes in Niger. There's now a court-case in Canada that is challenging the illegality of polygamy there on religious freedom grounds (see: http://www.washingtontimes.com/news/2011/jan/4/anti-polygamy-law-challenged-in-canada-court/). So, perhaps it's time to explore this matter a little further, as the traditional Western view of marriage is now in flux.
The arrival of Christianity didn't immediately result in the prohibitions of all-but-monogamous marriages among the believers. While we remember that the Old Testament patriarchs and kings took several wives and concubines, the New Testament never specifically forbid polygamy, except for the choosing of church elders, who were required to only have one wife (Titus 1:6). That suggests believers, or at least converts, could continue in polygamous marriage if they weren't church leaders. According to Wikipedia, a "one-man one-woman" model for the Christian marriage was advocated and promoted by Saint Augustine (354-439 AD) with his published letter The Good of Marriage. The letter was widely circulated and taught from in Western Christianity. However, it was only in 534 AD that the Roman Emperor Justinian criminalized all but monogamous man/woman sex within the confines of marriage. (See: http://en.wikipedia.org/wiki/Types_of_marriages ).
Certainly, in the annals of mission history, the question of what to do with a polygamous convert to Christianity has perplexed many missionaries. The choices were stark: to have the new believer continue in the Christian faith as a practitioner of polygamy—with the risk of the Church seeming to condone the practice in the society, but keeping his family intact—or to force the husband to dismiss all but one of his wives, thus denying these women (and their children) a stable home and perhaps forcing the abandoned wives into prostitution or some other unsavory means of survival. In some cases, you had a powerful polygamous local ruler accepting Christ, but because his multiple wives made him ineligible for church office, he would have to follow his monogamous subjects' leadership in the local church—a violation of all local cultural norms.
So in our post-modern world, how do we respond to other cultural and religious practices in marriage that differ from those of the West for the past 1500 years? The Canadian case suggests that the State must be able to prove that multiple marriage is harmful to society for it to be disallowed. If it can't make this case, multiple marriages would probably be legal for religious and individual freedom reasons.
During my years in Africa (including a nine-month stint in Nigeria in 1990-91), I've come across the following anecdotes involving polygamous households that I'd like to share:
a) In Hausa, the word for co-wife is “kishiya”, which also means “rival”.
b) It isn't unusual for the first wife, after several years of marriage and children, to encourage her husband to take a second wife because she wants the extra help with the household chores.
c) I saw a Nigerien pastor mourn the death of his father's second wife as if it was his own mother that had passed away (the two wives peacefully co-existed all of his life).
d) A Lebanese immigrant married two local women (who were cousins). They all became Christians later in life and all went to my church in Niamey.
e) A Nigerien elder was kicked out of church when he took a second wife. A different church teacher was disciplined, but stayed in the church, after admitting to keeping a concubine, whom he eventually left.
f) I've witnessed several Nigerien Christian women marry local Muslims only to be shocked and dismayed when their husbands take a second wife many years later. In most cases, these Christian women leave the marriage--and in accordance to Nigerien customary law—their children stay with the father. However, in Nigeria I've also seen Christian women stay among Muslim co-wives and raise their children as Christian in an otherwise Muslim home.
g) The most malnourished children in a Nigerien household are usually those whose mothers are no longer living in the family compound; i.e. the father's second or third wife is now responsible for feeding the offspring of a former wife who was divorced/left. These children are also less likely to continue in their schooling as a family's limited resources flow to the children whose mother is still in the home.
Perhaps one day these kinds of stories will also be commonplace in our North America communities and churches. Should that day arrive, I imagine the Western church will find itself looking to its Southern brothers and sisters for guidance.