Why should a man marry one woman only?
From the beginning, God intended for man to marry one woman. Our Lord Jesus Christ said, "He who made them at the beginning 'made them male and female" (Mt 19:4). There should be unity between them "Be joined to his wife, and the two shall become one flesh?" (Mt 19:5) with no separation "So then, they are no longer two but one flesh. Therefore what God has joined together, let not man separate" (Mt 19:6).
St. Paul says it very clearly,
An important biblical teaching in Christianity is the parallel of husband and wife with our Jesus Christ Christ and the Church in the Holy Book of Ephessians 5:22-23, which makes sense only with monogamy since our Lord Jesus will not have multiple brides. You may read more about this subject in His Holiness Pope Shenouda's book "The Law of the One Wife."
- "Let each man have his wife, and let each woman have her own husband" (1 Cor 7:2)
- "The wife does not have authority over her own body, but the husband does, and likewise the husband does not have authority over his own body, but the wife does" (1 Cor 7:4)
- "For this reason a man shall leave his father and mother and be joined to his wife, and the two shall become one flesh" (Eph 5:31)
- "He who loves his wife loves himself" (Eph 5:28)