Assuming the Old Covenant is obsolete and fulfilled (Heb 7:18-19), what is the biblical argument against allowing the practice of polygamy?
God's Standard Should Be Our Standard
The biblical standard regarding marriage, from Genesis to Revelation is
One groom, one bride, what e'er betide.
Or in slightly less old fashioned verbiage:
One husband, one wife, for life.
God never sanctioned polygyny in the Tanakh, nor did Jesus sanction it in the New Covenant. God's design from the beginning was stated in Genesis 2:24-25 and reiterated by Jesus in Matthew 19:3-12 and Mark 10:2-12. I teased the following statements from Genesis, Matthew, and Mark:
Marriage between one woman and one man was instituted by God.
The man and woman who marry are fully equal in the eyes of God, but they are different in significant ways. There are obvious similarities and differences, but the differences, in particular, complement each other.
Marriage involves two families, but it is the basis of a third family in its own right. In other words, there is a leaving and a cleaving and a conceiving (though not always).
God joins together two people, one man and one woman, and the two--not three or four or more--become one flesh.
Jesus sanctioned divorce when adultery violates the oneness of the marital relationship, but by the same token Jesus did not command divorce when either husband and/or wife commits adultery. In other words, he held out for the possibility of confession, forgiveness, and restoration of the relationship. Serial monogamy is not the biblical ideal, though Jesus obviously sanctioned (but did not command) remarriage after the death of one's spouse.
Jesus' emphasis on Moses in his discussion with the Pharisees who came to Jesus to test him with their question is significant. According to Jesus, "Moses permitted divorce" because of the hardness of the Israelis' hearts, neither because God had made provision for it in his original plan nor because it was legislated in the Mosaic law.
Is There Any Wiggle Room?
- The levirate spoken of in Deuteronomy 25:5-10 (levirate comes from the Latin word for brother-in-law) may seem like an exception to the "one husband, one wife, for life" rule, but it is not. As Constable noted in his explanation of this passage in the NET Bible "Notes":
"The Israelites were to practice levirate marriage only in cases where the brothers had lived together (v. 5) and the remaining brother was not already married. Living together meant living in the same area, not necessarily residing under the same roof. When another kinsman voluntarily assumed the responsibility of the surviving brother, that brother was apparently under no obligation to marry his sister-in-law (cf. Ruth 4). [my emphasis]
"There were several reasons for this provision. These reasons were the importance of descendants in God’s purposes for Israel, the welfare of the widow, and the demonstration of love for one’s brother (cf. Gen. 38)."
- Paul's insistence that a church elder or church deacon must be "the husband of but one wife," or as some folks interpret it, "a one-woman man," cannot be an argument from silence that it's OK for men who do not aspire to be leaders in the local church to have multiple wives. Furthermore, the decision of the polygynous man either to keep or separate from a second or third, or more wives, would be up to the husband, his wives, and the leadership of the local church, with each case judged and ruled upon based on its merits on a case by case basis (see 1 Timothy 2:1 ff.).
A Legitimate Inference Based on Every Example of Polygyny in the Bible
I feel confident in presenting this challenge to any reader of my answer to cite a Scripture passage (not the LDS Scripture, however, as I am not a Mormon) or give me an instance in the Bible in which polygyny was not characterized by familial infighting, deceit, jealousy, strife, violence, resentment, long-standing feuds, favoritism, hurt feelings, spiritual backsliding, or any one of a host of other negative aspects and consequences. There is simply not one instance.
What can we legitimately infer from the overwhelming evidence of negative consequences based on the instances of polygyny in the Bible? The only reasonable answer, at least in my opinion, is that God does not approve of it, and to flaunt God's standards regarding marriage is to court disaster. You can count on it!
The closest that any of the NT books come to even mentioning polygamy are the pastoral epistles when Paul says that a leader must be the husband of one wife.
2 Timothy 3:1-2 ESV The saying is trustworthy: If anyone aspires to the office of overseer, he desires a noble task. Therefore an overseer must be above reproach, the husband of one wife, sober-minded, self-controlled, respectable, hospitable, able to teach
Note that Paul says this is the requirement to be an overseer. He's not necessarily condemning or condoning polygamy as a general practice.
The answer is no, there is no Biblical basis in the New Testament for polygyny, or plural wives. But it is important to understand that while the old law has been fulfilled, it is only obsolete in that it has been superseded by a new law. The old law is of a lesser priesthood, and the new is of a higher priesthood.
"For the priesthood being changed, there is made of necessity a change also of the law." (Hebrews 7:12)
The lesser–Levitical, or Aaronic Priesthood is an appendage of the greater, or Melchizedek Priesthood. We live the higher law under the administration of the Melchizedek Priesthood, but the duties of the Aaronic Priesthood are not done away with.
From an LDS perspective, it is lawful for a man to have only one wife, unless the Lord commands otherwise by revelation.
"Wherefore, my brethren, hear me, and hearken to the word of the Lord: For there shall not any man among you have save it be one wife; and concubines he shall have none; For I, the Lord God, delight in the chastity of women. And whoredoms are an abomination before me; thus saith the Lord of Hosts. Wherefore, this people shall keep my commandments, saith the Lord of Hosts, or cursed be the land for their sakes. For if I will, saith the Lord of Hosts, raise up seed unto me, I will command my people; otherwise they shall hearken unto these things." (Jacob 2:27–30).
By revelation, plural marriage was practiced in Old Testament times and in the early days of the restored Church by the direction of the prophet who held the priesthood keys (D&C 132:34–40, 45). It is no longer practiced in the Church (D&C OD—1); today, having more than one wife is incompatible with membership in The Church of Jesus Christ of Latter-day Saints.
The only time polygamy, or more specifically polygyny is allowed, is when the Lord commands it. The law of Moses is an example of when the Lord commanded it. Christ fulfilled the law of Moses, but did not make every ordinance belonging to the priesthood obsolete. There will be a time when all the ordinances of the priesthood, like sacrifice, and possibly plural marriage, will be restored:
“These sacrifices, as well as every ordinance belonging to the Priesthood, will, when the Temple of the Lord shall be built, and the sons of Levi be purified, be fully restored and attended to in all their powers, ramifications, and blessings. This ever did and ever will exist when the powers of the Melchizedek Priesthood are sufficiently manifest; else how can the restitution of all things spoken of by the Holy Prophets be brought to pass. It is not to be understood that the law of Moses will be established again with all its rites and variety of ceremonies; this has never been spoken of by the prophets; but those things which existed prior to Moses’ day, namely, sacrifice, will be continued.” (Teachings, pp. 172–73.)