I have a fundamentalist friend who claims that polygamy is okay because it was accepted in the Old Testament and never condemned in the New Testament. He brought up the passage instructing deacons to have only one wife as an implicit argument that the early Church accepted polygamy. I countered that this passage was a discipline of the early Church not to raise widowers who had remarried to Holy Orders (remarrying was considered low class). However, I could not think of any N.T. passages condemning polygamy. Are there any such passages? Barring that, do we have extrabiblical Christian sources condemning such behaviour?
*Catechism of the Catholic Church * no. 2387:
The predicament of a man who, desiring to convert to the Gospel, is obliged to repudiate one or more wives with whom he has shared years of conjugal life, is understandable. However polygamy is not in accord with the moral law." [Conjugal] Such a communion is radically contradicted by polygamy; this, in fact, directly negates the plan of God which was revealed from the beginning, because it is contrary to the equal personal dignity of men and women who in matrimony give themselves with a love that is total and therefore unique and exclusive."180 The Christian who has previously lived in polygamy has a grave duty in justice to honor the obligations contracted in regard to his former wives and his children.
Fostering the nobility of marriage and family
“Yet the excellence of this institution is not everywhere reflected with equal brilliance, since polygamy, the plague of divorce, so-called free love and other disfigurements have an obscuring effect. In addition, married love is too often profaned by excessive self-love, the worship of pleasure and illicit practices against human generation. Moreover, serious disturbances are caused in families by modern economic conditions, by influences at once social and psychological, and by the demands of civil society. Finally, in certain parts of the world problems resulting from population growth are generating concern.
Thus a man and a woman, who by their compact of conjugal love “are no longer two, but one flesh” (Matt. 19:ff), render mutual help and service to each other through an intimate union of their persons and of their actions. Through this union they experience the meaning of their oneness and attain to it with growing perfection day by day. As a mutual gift of two persons, this intimate union and the good of the children impose total fidelity on the spouses and argue for an unbreakable oneness between them.”
*Familiaris Consortio * (On the Family) no. 19:
The first communion is the one which is established and which develops between husband and wife: By virtue of the covenant of married life, the man and woman are covenant of “are no longer two but one flesh” Mt. 19:6; cf. Gn. 2:24] and they are called to grow continually in their communion through day-to-day fidelity to their marriage promise of total mutual self-giving.