However, you have not even provided evidence that God approved of polygamy. It would be pointless to do so, because there's no evidence that God exists. Belief in God is based on faith - "evidence" would actually destroy the foundation of religion.
Mind you, I'm not criticizing anyone's belief system - everyone is free to believe in whatever they wish.
But religion is based on faith, on that which you believe in the absence of facts, proof, etc. The minute you start talking "evidence", you place things under a microscope, under logic, under the scientific method...which would make god finite, definitive, subject to measurement, etc.
Kevin