Q: “I have been reading in I and II Samuel and about David having several wives. At what point in time was it considered adultery?”
A: Though we know that David had at least eight wives during his life (Michal, Ahinoam, Abigail, Maacah, Haggath, Abital, Eglah, and Bathsheba—several concurrently), we find no approval of these polygamous relationships in the sight of God. It is very clear from Genesis 2:24 in the usage of the singular “man” and “his wife” that God had from the beginning established monogamy as the proper marriage relationship. Furthermore, Jesus in the New Testament clarifies the Genesis passage when He says: “For this reason a man will leave his father and mother and be united to, his wife, and the two wil1 become one flesh. So they are no longer two but one”, (Matthew 19:5 NIV). The fact that polygamy was practiced by a number of “heroes” of faith” (Abraham, Jacob, David, Solomon, etc.) in Old, Testament times does not justify the adulterous act. It was not God-pleasing nor had God intended it as an example for believers to follow. In fact, the jealousies and dissensions and religious degeneration that often resulted from the practice of polygamy especially is evident in the case of Solomon, “As Solomon grew old his wives turned his heart after other gods” (I Kings 11:4)
The real question, which we have in retrospect, is: How could a man like David be commended for his faith even as he was living in an adulterous relationship? Well, surely the commendation given to David by God in Scripture (I Kings 14:8, 15:3-5) was always in spite of any failure to live up to the holy commands of the Lord. Just as with Abraham, David too believed that the righteousness of the Messiah was his salvation before God, and God then, “credited it to him as righteousness.” Once the polygamous relationships were entered into by David, and thus marriage vows had been spoken, divorcing all the women except the original would have simply compounded sin upon sin. As the saying goes, “Two wrongs don’t make a right.”
Other pertinent passages which show God forbids the bigamy and polygamy still practiced by some today are: Eph. 5:22-23; I Tim. 3:2; 12; 5:9; Rom. 7:2, I Cor. 7:9.