All about Biblical Marriage

Matthew 19:4-6 He (Jesus) answered, “Have you not read that he who created them from the beginning made them male and female, and said, ‘Therefore a man shall leave his father and his mother and hold fast to his wife, and the two shall become one flesh’? So they are no longer two but one flesh. What therefore God has joined together, let not man separate.”

Genesis 2:18-25 Then the Lord God said, “It is not good that the man should be alone; I will make him a helper fit for[e] him.” -- But for Adam there was not found a helper fit for him. So the Lord God caused a deep sleep to fall upon the man, and while he slept took one of his ribs and closed up its place with flesh. And the rib that the Lord God had taken from the man he made into a woman and brought her to the man. Then the man said,

“This at last is bone of my bones and flesh of my flesh; she shall be called Woman, because she was taken out of Man.” Therefore a man shall leave his father and his mother and hold fast to his wife, and they shall become one flesh. And the man and his wife were both naked and were not ashamed.

The definition of marriage: becoming one flesh

It is clear from the original establishement of marriage that it has nothing to do with religion, community or even romantic love. The act and reality of "becoming one flesh" is the foundational truth of marriage. This is later recognized in scriptures such as

Exodus 22:16: If a man seduces a virgin who is not betrothed and lies with her, he shall give the bride-price for her and make her his wife.

In other words: although the man-made cultural concept of marriage can be useful, it too must be made to follow the deeper underlying reality of "being one flesh", which - when it has taken place - constitutes marriage before God, and we should respect it. This is worth repeating:

What therefore God has joined together, let not man separate. Matthew 19:6

Multiple wives

1 Cor. 11:3 But I want you to understand that the head of every man is Christ, the head of a wife is her husband, and the head of Christ is God.

Abraham had Sarah, Hagar and Keturah (Genesis 11:29; 16:3; 25:1). Jacob had Leah, Rachel, Bilhah, Zilpah (Genesis 30) David had Ahinoam, Abigail, Haggith, Abital, Eglah, Michal, Maaca, Bathsheba and other women (1-2 Samuel)

There is no prohibition in the bible against a man having multiple wives. This is a simple fact. It seems the headship of the man over his wife/wives is a key factor: there is no conflict as there is only one head. Similarly, it is forbidden for a woman to leave her husband to be joined to another man. A woman, therefore, is simply forbidden from having multiple husbands.

But it's not just me. Let's listen to the great protestant reformer, Martin Luther: Letter to Chancellor Gregory Bruck, January 13, 1524 (De Wette II, 459, pp. 329, 330)

I confess that I cannot forbid a person to marry several wives, for it does not contradict the Scripture. If a man wishes to marry more than one wife he should be asked whether he is satisfied in his conscience that he may do so in accordance with the Word of God. In such a case the civil authority has nothing to do in the matter.

Now there are hints that this is not the ideal arrangement. Appart from the fact that God only created one woman for Adam our father, there are two places in scripture where the number of wives is restricted: for kings and for new testament church leaders. Apparently there are at least practical reasons to only have one wife (or in the case of a king, "not many wives", what ever that means).

Deuteronomy 17:17 And he (king) shall not acquire many wives for himself, lest his heart turn away, nor shall he acquire for himself excessive silver and gold.

1 Tim 3:2-3 Therefore an overseer must be above reproach, the husband of one wife, sober-minded, self-controlled, respectable, hospitable, able to teach, not a drunkard, not violent but gentle, not quarrelsome, not a lover of money.

Adultery

The basic definition of adultery is simple: having sex with another man's wife. Leviticus 20:10 If a man commits adultery with the wife of his neighbor, both the adulterer and the adulteress shall surely be put to death.

This extends to remarrying: But I say to you that everyone who divorces his wife, except on the ground of sexual immorality, makes her commit adultery, and whoever marries a divorced woman commits adultery.

Here there is an important distinction: