Many kings in the Bible had more than one wife, even hundreds. Does the Bible say polygamy is fine?
The Bible reports on many events and practices that it doesn’t condone. God's design for marriage is seen in passage in Genesis 2 containing the creation of Adam and Eve and His prescriptions for their life together. When questioned about divorce in Matthew 19, Jesus referred to this passage and confirmed that marriage was about God joining a husband and wife together. Whenever God gives direction for marriage in the Bible, it’s always in the singular.
In an extremely patriarchal culture where women were rarely allowed to own property, women had few options for survival outside of a family structure. Polygamy was practiced within and without Hebrew culture during the time of the Old Testament and it continues today in other cultures around the globe. That said, kings were warned against "multiplying wives to themselves" in Deuteronomy 17:17. The New Testament makes it clear that God's intention for marriage has always been one man and one woman. Titus 1:6, 1 Timothy 3:2 and 3:12, within lists that should apply to all Christians, state that leaders in the church should be "a husband of one wife", which is literally in the text "a one woman man."