The Bible shows that God’s original design for marriage was one man and one woman. In the beginning, when God created marriage, He joined Adam and Eve together and said that a man shall leave his father and mother and be united with his wife, and the two shall become one flesh. This shows that the first pattern of marriage established by God was monogamy. Jesus also referred to this same teaching when speaking about marriage, emphasizing the unity between one man and one woman.
In the Old Testament we see that some people practiced polygamy. Men like Abraham, Jacob, David, and Solomon had more than one wife. The Bible records these events, but it does not always mean that God approved of them. In many of these situations, polygamy brought conflict, jealousy, and family problems. For example, the rivalry between Leah and Rachel in Jacob’s family and the troubles in David’s household show the difficulties that came from having multiple wives.