Martin Luther struggled greatly with the relationship of God’s sovereignty to human free will and sin. In fact, one of the greatest books ever written on the subject, The Bondage of the Will, is from Luther’s pen. When Luther grappled with this issue, he especially struggled with the Old Testament passages where we read that God hardened Pharaoh’s heart (Ex. 4:21; 7:3–4, 13–14, 22–23; 8:15, 19, 30–32; 9:27–10:2; 10:16–20, 24–28).