Pete, as I stated above, I, as a Christian, can find absolutely no prohibition of polygamy in the Bible. Plenty against divorce (which so many Christians now accept), some against homosexuality, but nothing against polygamy! Nor is there any clear expression of a one-man-one-woman "norm".

Until the late middle ages, marriage was a civil affair. No religious ceremony was involved (as a necessity--a blessing might be given). It became a religious thing at the service of the state who wanted an easier way to track property and inheritance rights. Even the Puritans (like the founding fathers) rejected the religious form of marriage.