In the early days of Islam (say, up to the Battle of Tours in 732 A.D.), polgamy had a certain dynamic logic to it. Here's how it worked--
A man could have up to four wives. It is important to understand that before Muhammad, under the various animist and other Arabian tribal traditions, men could have any number of wives. Muhammad's prexcription limited it to four.
Under this system, only the prosperous could have more than one wife. The more men there were with multiple wives, the more men at the other end of the economic scale had to remain without wives at all. It was thought, correctly, that this sort of sexual deprivation and frustration would make them good warriors; a certain amount of plunder was allowed, and it also became a way for these young men to become prosperous themselves, but while they were poor warriors, they expanded the Islamic lands all through the southern half of the Mediterranean, and then, into Europe, both through the Balkans and through Spain--as well as eastward to Mesopotamia and Persia and further.
At the same time, in the early days, few families maintained great wealth unless there was genuine talent in the family. The more wives a man had, the more children he was likely to have, and that meant that upon his death, his wealth would be distributed among the sons. Each son, therefore, would be considerably less prosperous than the father, and only talent, ability, and skill could preserve and expand the family wealth. This meant that there was a strongly meritocratic element in the society, which stood the early Islamic world in good stead.
As soon as the rapid expansion stopped, though, the system began to fall apart and various corruptions of doctrine and morals and economic life began to manifest themselves. Progressive clerics responded with various ideas, among them the notion that a man was only supposed to have sexual relations with one wife, and that the allowance of multiple wives had really been just a method of providing for widows made destitute by the distribution of a deceased husband's property to his sons.
In places like Colorado City, OTOH, you have nothing like the exuberant, expansive dynamic of early Islam, or, for that matter, early Mormonism. It is a very enclosed, insular society. In Colorado City, men take child brides, and they don't limit it to four, either. Many of the families have income low enough that they qualify for and receive food stamps, and, often, medicaid, if not cash assistance. At the same time, they find various excuses to declare young men, who threaten this system, unworthy and expel them.
Natural law tells me that this is a false religion. The Christian tradition is that salvation is for all people, and if some people, especially the young men, have to be kicked out for the dynamic of the society to survive, then it is not a religion for all people, and therefore is violative of the basic principles of Christianity.
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