The polygamy thing works great for new religions because it is a sure fire way to easily create more adherents from a small amount of stock. Indoctrinating children from birth is way easier than converting adults.

Now imagine how much the christian god’s mind was changed by the roman government

My favorite argument is that I was given access to Super God when I a child. Which gives me access to Super Heaven when I die. It’s waaaaay better that regular heaven. You keep praying to regular god or whatever, you mud dwelling peasant. I’ll be looking down on you from Super Heaven and laughing for Extra Eternity.