This is the reasoning of the Jehovah's Witnesses:
*** cl chap. 6 pp. 59-61 Destructive Power—“Jehovah Is a Manly Person of War” ***
Divine War Versus Human Conflicts
5 Nearly three hundred times in the Hebrew Scriptures and twice in the Christian Greek Scriptures, God is given the title “Jehovah of armies.” (1 Samuel 1:11) As Sovereign Ruler, Jehovah commands a vast army of angelic forces. (Joshua 5:13-15; 1 Kings 22:19) The destructive potential of this army is awesome. (Isaiah 37:36) The destruction of humans is not pleasant to contemplate. However, we must remember that God’s wars are unlike petty human conflicts. Military and political leaders may try to attribute noble motives to their aggression. But human war invariably involves greed and selfishness.
6 In contrast, Jehovah is not driven by blind emotion. Deuteronomy 32:4 declares: “The Rock, perfect is his activity, for all his ways are justice. A God of faithfulness, with whom there is no injustice; righteous and upright is he.” God’s Word condemns unbridled rage, cruelty, and violence. (Genesis 49:7; Psalm 11:5) So Jehovah never acts without reason. He uses his destructive power sparingly and as a last resort. It is as he stated through his prophet Ezekiel: “‘Do I take any delight at all in the death of someone wicked,’ is the utterance of the Sovereign Lord Jehovah, ‘and not in that he should turn back from his ways and actually keep living?’”—Ezekiel 18:23.
7 Why, then, does Jehovah use destructive power? Before answering, we might call to mind the righteous man Job. Satan challenged whether Job—really, any human—would keep his integrity under trial. Jehovah answered that challenge by allowing Satan to test Job’s integrity. As a result, Job suffered illness, loss of wealth, and loss of his children. (Job 1:1–2:8) Unaware of the issues involved, Job mistakenly concluded that his suffering was unjust punishment from God. He asked God why He had made him a “target,” “an enemy.”—Job 7:20; 13:24.
8 A young man named Elihu exposed the flaw in Job’s reasoning, saying: “You have said, ‘My righteousness is more than God’s.’” (Job 35:2) Yes, it is unwise to think that we know better than God or to assume that he has behaved unfairly. “Far be it from the true God to act wickedly, and the Almighty to act unjustly,” Elihu declared. Later, he said: “As for the Almighty, we have not found him out; he is exalted in power, and justice and abundance of righteousness he will not belittle.” (Job 34:10; 36:22, 23; 37:23) We can be sure that when God fights, he has good cause for doing so. With that in mind, let us explore some of the reasons why the God of peace sometimes assumes the mantle of a warrior.—1 Corinthians 14:33.
Why the God of Peace Is Compelled to Fight
9 After praising God as “a manly person of war,” Moses declared: “Who among the gods is like you, O Jehovah? Who is like you, proving yourself mighty in holiness?” (Exodus 15:11) The prophet Habakkuk similarly wrote: “You are too pure in eyes to see what is bad; and to look on trouble you are not able.” (Habakkuk 1:13) Although Jehovah is a God of love, he is also a God of holiness, righteousness, and justice. At times, such qualities compel him to use his destructive power. (Isaiah 59:15-19; Luke 18:7) So God does not blemish his holiness when he fights. Rather, he fights because he is holy.—Exodus 39:30.
Consider the situation that arose after the first human couple, Adam and Eve, rebelled against God. (Genesis 3:1-6) Had he tolerated their unrighteousness, Jehovah would have undermined his own position as Universal Sovereign. As a righteous God, he was obliged to sentence them to death. (Romans 6:23) In the first Bible prophecy, he foretold that enmity would exist between his own servants and the followers of the “serpent,” Satan. (Revelation 12:9; Genesis 3:15) Ultimately, this enmity could only be resolved by the crushing of Satan. (Romans 16:20) But that judgment act would result in great blessings for righteous mankind, ridding the earth of Satan’s influence and opening the way to a global paradise. (Matthew 19:28) Until then, those who sided with Satan would constitute an ongoing threat to the physical and spiritual well-being of God’s people. On occasion, Jehovah would have to intervene.
11 The Deluge of Noah’s day was a case of such intervention. Says Genesis 6:11, 12: “The earth came to be ruined in the sight of the true God and the earth became filled with violence. So God saw the earth and, look! it was ruined, because all flesh had ruined its way on the earth.” Would God allow the wicked to snuff out the last vestige of morality left on earth? No. Jehovah felt obliged to bring a global deluge to rid the earth of those who were bent on violence and immorality.
It was similar with God’s judgment against the Canaanites. Jehovah revealed that out of Abraham would come a “seed” through which all the families of the earth would bless themselves. In harmony with that purpose, God decreed that Abraham’s offspring would be given the land of Canaan, a land inhabited by a people called the Amorites. How could God be justified in forcibly evicting these people from their land? Jehovah foretold that the eviction would not come for some 400 years—until “the error of the Amorites” had “come to completion.” (Genesis 12:1-3; 13:14, 15; 15:13, 16; 22:18) During that period of time, the Amorites sank deeper and deeper into moral corruption. Canaan became a land of idolatry, bloodshed, and degraded sexual practices. (Exodus 23:24; 34:12, 13; Numbers 33:52) The inhabitants of the land even killed children in sacrificial fires. Could a holy God expose his people to such wickedness? No! He declared: “The land is unclean, and I shall bring punishment for its error upon it, and the land will vomit its inhabitants out.” (Leviticus 18:21-25) Jehovah did not kill the people indiscriminately, however. Rightly disposed Canaanites, such as Rahab and the Gibeonites, were spared.—Joshua 6:25; 9:3-27.
Fighting in Behalf of His People [I skipped some of the paragraphs to get to the point]
16 Does Jehovah’s interest in defending his name mean that he is cold and self-centered? No, for by acting in accord with his holiness and love of justice, he protects his people. Consider Genesis chapter 14. There we read of four invading kings who kidnapped Abraham’s nephew Lot, along with Lot’s family. With God’s help, Abraham executed a stunning defeat of vastly superior forces! The account of this victory was likely the first entry in “the book of the Wars of Jehovah,” evidently a book that also documented some military encounters that are not recorded in the Bible. (Numbers 21:14) Many more victories were to follow.
17 Shortly before the Israelites entered the land of Canaan, Moses assured them: “Jehovah your God is the one going before you. He will fight for you according to all that he did with you in Egypt.” (Deuteronomy 1:30; 20:1) Starting with Moses’ successor, Joshua, and continuing on through the period of the Judges and the reigns of the faithful kings of Judah, Jehovah indeed fought for his people, giving them many dramatic victories over their enemies.—Joshua 10:1-14; Judges 4:12-17; 2 Samuel 5:17-21.
18 Jehovah has not changed; nor has his purpose to make this planet a peaceful paradise changed. (Genesis 1:27, 28) God still hates wickedness. At the same time, he dearly loves his people and will soon act in their behalf. (Psalm 11:7) In fact, the enmity described at Genesis 3:15 is expected to reach a dramatic and violent turning point in the near future. To sanctify his name and protect his people, Jehovah will once again become “a manly person of war”!—Zechariah 14:3; Revelation 16:14, 16.
19 Consider an illustration: Suppose that a man’s family was being attacked by a vicious animal and that the man jumped into the fray and killed the violent beast. Would you expect his wife and children to be repelled by this act? On the contrary, you would expect them to be moved by his selfless love for them. In a similar way, we should not be repelled by God’s use of destructive power. His willingness to fight to protect us should increase our love for him. Our respect for his unlimited power should deepen as well. Thus, we can “render God sacred service with godly fear and awe.”—Hebrews 12:28.