In current debates about same-sex marriage, the assumption that marriage has always been between ‘one man and one woman’ has been disputed.  What about marriage in the Old Testament?  Did not David (and others) have more than one wife?  Does not that fact undermine the assumption?

Monogamy was established by God in creation (Gen. 2:18–25), reaffirmed by Christ in his teachings about marriage (Matt. 19:3–12 // Mark 10:2–12), and echoed in the later NT when it touches on marriage (1 Cor. 6:16; 7:1–2; Eph. 5:22–33; 1 Tim. 3:2)

The first recorded instance of polygamy is found in Genesis 4:19 (Lamech, who also became a murderer).  See also Gen 4:19; 16:3; 29:30.  Abraham, Jacob.

Exodus 21:10 says that if a man marries a second wife, he must not deprive his first wife of food, clothing, or marital rights.  (N.B. this interpretation is disputed).

Hannah, 1 Sam 1 – one of two wives.

King David had many wives, 1 Chronicles 3.

King Solomon took even larger numbers of wives and concubines, 1 Kings 11:3.

The key text of Genesis 2:18-24 teaches that marriage is indeed between one man and one woman.  This is emphatically endorsed by Jesus (in the context of a discussion about adultery, Mt 5:27-32).

Deuteronomy 17:17 prohibits a king from having ‘many wives’.

Polygamy appears to have been uncommon amongst commoners in the OT, not least because poorer people would not have been able to afford the bride price.

Monogamy is implied in most OT laws, Ex 20:17; 21:5; Lev 18:8, 16, 20; 20:10; Num 5:12; Deut 5:21.

Scripture does not necessarily endorse everything that it describes.  The Bible never endorses polygamy.  It describes the misfortune and strife that frequently occur in polygamous families.  It regulates its worst excesses, Exodus 21:7–11, Leviticus 18:18, Deuteronomy 21:15–17 and 2 Samuel 12:7–8.

‘To contend, as some do, that legislation on rights within polygamy tacitly condones polygamy makes about as much sense as saying that Deuteronomy 23:18 approves of harlotry since it prohibits bringing the wages earned by harlotry into the house of the Lord for any vow!’ (HSB)

‘Polygamy seems to have been the preserve of exceptionally powerful and wealthy men whose sprawling households of wives and half-related children often were filled with favored and disfavored wives and children and vexed by the inevitable intrigues, jealousies, and hard feelings.’ ((DSE)  Solomon’s extreme polygamy receives stern condemnation in Scripture because it was the avenue by which idolatry infected Israel at the Zenith of its power.

Monogamy as a norm is assumed in passages where a man’s ‘wife’ is referred to, as in Jer 5:8; Mal 2:14.

We must distinguish between a command, a prohibition and a concession.

Cultural considerations

Polygamy was a status symbol in the Ancient near East, and a means of a king ensuring the continuation of his dynasty.

Polygamy did serve a useful social function whenever the male population was decimated by war (cf. Is 4:1).

In the NT, monogamy appears to have been the rule, although some rulers, such as Herod,