You are making quite a few assumptions about me. First, you seem to think I am a Christian. I'm not, just a student of history, society and religion.

Second, Atwood is talking about whole totalitarian societies, not small extremist sects, and in modern times, e.g. Saudi Arabia, not in Old Testament times. Most of the world was polygamous originally, and of course that includes ancient Jews.

Not only am I not ignorant about the history of monogamy, I made similar comments here myself many times. It actually came from the Greeks, which the Romans imitated, and we inherited it through the Roman Empire. 

The Jews adopted it because they were part of the Roman Empire. Once adopted over 2000 years ago though, it became the norm in both religions, and the theology developed accordingly.

Meanwhile, Islam reduced the number of allowed wives from infinite to "just four", that was an improvement for women, but they stuck to 4, but men could have harems of non-wives.