So you expect it is America's duty to change the customs of the Muslim world?
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God said, to a man, "Be fruitful and multiply". The best way for a guy to do this is to emulate King Solomon or kin David and have huge harem: impregnate many women simultaneously. Mohammad figured four was an adequate number of wives.
When women get older, they get smarter, so it is best to impregnate them young. How old was Jesus' Mother? Most say about fourteen or fifteen. That was the custom in the Middle East, and it is still the custom.