How does Rasheed, using religion, justify abusing his wives?

Rasheed uses his religion to stifle his wives, imposing a mixture of tradition and extremities to assert himself as head of household. Mariam was a replacement, her purpose was to bear children, but she proved unable to fulfill Rasheed's wishes, and over time he came to resent her. Think about the fact that it isn't until far into their relationship that Rasheed forced her to wear a bourka. He didn't initially require Mariam to do so, but as I see it, suddenly made the decision in a bid for authority. It doesn't seem to me that the requirement stemmed from his religion, as that would have made it a requirement from the beginning. Ot seems to me, he forced her because he could..... he used religion to implement control.