It's absurd and completely fantastical. the entire premise of the sexual enslavement of these women was based on an event where somewhere in the Old Testament someone used a surrogate to produce a child. This society hijacked that event And turned it into a command, something which the Old Testament never did.
Right: historically speaking, the Old Testament has been more often used to justify sexual enslavement of wives by their husbands; sexual enslavement of unmarried women was (usually) frowned upon.
Personally, I don’t get too hung up on the particular doctrines of the Gilead regime in the book/movie. Instead, I try to look at the overall themes.
For the book itself, it's largely a commentary on the then-contemporary situation Atwood saw. Remember that Atwood - a Canadian - wrote this book several years before the 1988 Canadian Supreme Court decision that struck down our country's abortion laws. She wasn't so much writing speculative fiction about how a male Christian establishment might one day control the reproductive choices of women; it was talking - in a veiled way - about how a male Christian establishment
was controlling the reproductive choices of women at the time. The book is in large part her commentary on how awful and dehumanizing what she saw around her was.
That being said, I think Atwood's exegesis to create the doctrines and laws of "the Republic of Gilead" is no less solid than a lot of the stuff from real mainstream churches.
this is the society depicted in that show is not based on Christianity, but on a totalitarian regime that twists Christianity to its own ends. much in the same way that Kim Jong Un twisted Anne Frank's diary to further their propaganda with their school children. I can see an already totalitarian regime using Christianity toward whatever nefarious end, but I cannot see any society evolving into what we see in that show due to Christianity.
Has there ever been a Christian regime that didn't end up oppressive?