God never promoted polygamy or intended that His followers should engage in that practice. Although the Old Testament records that several of the patriarchs practiced polygamy, it was never in accordance with God's will and His intent for marriage. When a man took more than one wife, curses and punishment were the consequence.
Abraham sinned when he had sexual relationships with Sarah's maid Hagar. This was not only a sin because he lacked faith in God that He could give him a son through his wife Sarah, who was barren, but he also sinned, because he was married to Sarah and therefore committed adultery with Sarah's maid.
We do. It is important to understand what the Bible has to say about the subject of interracial marriages.
"You are the light of the world. A city that is set on a hill cannot be hidden."
-Matthew 5:14