HA!True Christians live by the Law of Christ, not the Law of Moses.
Those ancient Jews were allowed more than one wife, because they wanted it that way, not God or even Moses. Jesus explained they were rebellious from the start. Matthew 19:8,9
The Jews had no permission to have a second wife, the law covered the consequences if he did take one, or if he did anything he wasn't suppose to do.
Like Jesus said, if you look at a woman to have a passion for her, you already committed adultery in your heart. You must have clean thoughts to have a clean heart. Matthew 15:19
17Think not that I am come to destroy the law, or the prophets: I am not come to destroy, but to fulfil.
18For verily I say unto you, Till heaven and earth pass, one jot or one tittle shall in no wise pass from the law, till all be fulfilled.
19Whosoever therefore shall break one of these least commandments, and shall teach men so, he shall be called the least in the kingdom of heaven: but whosoever shall do and teach them, the same shall be called great in the kingdom of heaven.
That means the OT as well.
According to the Bible God does not change so why would his laws?
THe next person that I see wearing a Polyblend piece of clothing is getting a rock to the head.