During a conversation about traditional Mormon sects, someone requested clarification on my assertion that the Bible does not anywhere state that polygamy–a man having two or more wives–is unlawful, a transgression, technically a sin, is not a breaking of the original marriage covenant (but rather a second and additional but no less valid marriage covenant), and therefore not the same as adultery. Based on what is explicitly stated, being a polygamist only disqualifies a man from being an elder/overseer/leader of a local church. The Bible doesn’t make a big deal about it. And when pagan polygamists repent from sin and idols unto God and believe upon the Lord Jesus Christ, they are supposed to destroy their idols and their occultic book of spells, but they’re not supposed to leave their second, third, fourth, fifth, etc. wives.
Based on the way Jesus answered questions about marriage (see Mt. 19). the original God-given precedent and design and ideal is one man and one woman (i.e., Adam + Eve). Other kinds of sexual relationships fall short. Under Israelite covenant law, the death penalty was prescribed for some of aberrant forms of sexuality (see Lev. 18). This list includes adultery but not polygamy. Even though polygamy is neither ideal nor recommended, it seems to be something that God seemed to tolerate.
Even though the Bible does not ever explicitly say that polygamy is a sin/transgression, the Bible shows implicitly, through its story telling of several true stories of polygamist men in the Older Testament, that polygamy never works out well and, in so far as “a word to the wise is sufficient,” should be avoided.
This stance (which I take to be that of Abraham, Moses, David, Solomon, and the apostles) is quite different than the original stance of the Mormon cult leaders, who considered polygamy important. It is also different than the current stance of the LDS church (one of the main offshoots of the Mormon phenomena) which persecutes and banishes the traditionalists who might marry more than one woman. It is also a little different than the popular evangelical Christian view from the 1800s to the 2020s.
For the sake of getting a sanity check, I looked at a couple reputable reference books from the Protestant evangelical tradition. Perhaps they say it better than I did.
From The New Bible Dictionary (Eerdmans, 1962):
And from The Evangelical Dictionary of Theology (Elwell, ed., Baker, 1984):
