Everyone who seeks to share the gospel will face this question sooner or later: “If your God is a God of love, how could He command the slaughter of men, women and children in the Old Testament—for example, such passages as Deuteronomy 20:17?”
A cursory reading of the Old and New Testaments may give the impression that the God of the OT and the Jesus of the NT are entirely different. One seems to be full of vengeance and ready to judge, while the other is full of love and ready to forgive. Obviously, this cannot be the case since the Lord Jesus is the full revelation of the Father.
Notice the following key points:
1. The testimony of the OT is that God is “ready to pardon, gracious and merciful, slow to anger, and of great kindness, and forsookest them not” (Neh 9:17). See also Ps 103:8; 145:8;Joel 2:13; and Jonah 4:2. This longsuffering was not only to Israel but also toward Gentile nations. The last verse refers to the sparing of Ninevah, and we know the Lord withheld judgment on one Canaanite nation “for the iniquity of the Amorites [was] not yet full” (Gen 15:16). This judgment prophesied in the days of Abram was withheld for almost 1,000 years until the days of King Saul.
2. The testimony of the NT is that judgment is also surely coming in this age as well: “the Lord Jesus shall be revealed from heaven with his mighty angels, in flaming fire taking vengeance on them that know not God, and that obey not the gospel of our Lord Jesus Christ” (2 Thess 1:7-8).
3. God has used one nation to bring judgment on another. The judgment of the Canaanites coincided with the exodus of the Israelites, just as the rise of the Assyrians coincided with God’s judgment on the Israelites. God is fair, and in the end will be seen to have been just in all His dealings.
4. God has the right to judge His creatures. A key question is asked in Romans 3:5, “Is God unrighteous who taketh vengeance?” Here is the crux of the matter. If there is to be justice in the universe, it cannot be left to the law courts of men. Even those who seek to be just often find true justice beyond them. How can human law serve justice when someone has murdered a child? The child cannot receive justice at the hands of men.
Only the Lord Jesus, into whose hands have been given all judgment (Jn 5:22; Acts 17:31) will be able to set things right in the world.