"Polygamy is a lack of realization of sex; it is like a man plucking five pears in mere absence of mind."--G.K. Chesterton (The Ethics of Elfland)
Alice C. Linsley
Read the rationale at the Pro-Polygamy blog, here. Polygamy and Christianity simply do not go together, ask any Christian bishop living in countries where polygamy is practiced.
For clarification we are speaking of multiple wives, not multiple husbands. The technical term in this case is "polygyny" not polygamy. Polygamy refers to the practice of having multiple spouses and is not gender specific. Polygyny is the practice of multiple wives and that is the practice in question.
Polygyny is an ancient practice traced back to Africa. Among Abraham's Nilo-Saharan people only rulers had multiple wives. Terah, Abraham's father, had 2 wives. Abraham had 2 wives. Very likely Isaac had 2 wives, and Jacob had 2 wives.
The rulers among Abraham's people had only 2 wives and the wives lived in separate households geographically removed, and on a north-south axis. One wife was a half-sister and the other was a patrilineal parallel cousin.
In Africa, when a man's economic and social status increases he might take a second and even a third wife. Rarely does a man have more than 3 wives. The number 3 represents the ideal number because 3 first-born sons is regarded as a unity or a kingdom. That is why there are so many instances of 3 sons listed in the Hebrew Scriptures.
The Hebrew prophets criticized Solomon for having many wives and concubines. In doing so, Solomon departed from the marriage and ascendancy pattern of his Horite ancestors.
Wives and concubines have different legal and social status. Abraham had two wives (Sarah and Keturah) and two concubines (Hagar and Masek). This was the norm for Horite rulers.
The Church very early distanced itself from polygamy because it had become a way of seeking worldly status. Rulers or elders in the Church were strictly forbidden to have more than one wife.
Related reading: No, You can't take another wife!