Deuteronomy 18:9-14 “When you come into the land that the Lord your God is giving you, you shall not learn to follow the abominable practices of those nations. 10 There shall not be found among you anyone who burns his son or his daughter as an offering, anyone who practices divination or tells fortunes or interprets omens, or a sorcerer 11 or a charmer or a medium or a necromancer or one who inquires of the dead, 12 for whoever does these things is an abomination to the Lord. And because of these abominations the Lord your God is driving them out before you. 13 You shall be blameless before the Lord your God, 14 for these nations, which you are about to dispossess, listen to fortune-tellers and to diviners. But as for you, the Lord your God has not allowed you to do this."
So often when people object to God's judgment, they point to the Old Testament and use words like 'genocide.' They see that God brings his people into a land that he gives them and if these nations will not move out of the way, they are to be dispossessed. In some instances, they are wiped out. What seems like cruelty to skeptics is the very justice that we all who ignore God and his holiness deserve.
When God brought his people into the land, they were to be his people. He was to be their God. They were to live for their God and enjoy his presence with them. They were to be holy as the Lord their God is Holy. That holiness was to be a display of God's fame and glory to the nations. It was to invite them to repent of their sinful ways and find forgiveness in the grace and mercy of the one true living God. Israel was to maintain that holiness and so often we see it displayed in the words that describe what is unclean and must be put outside the camp.
There was to be an absolute display of the purity and holiness of God to live within the family of God. If an Israelite touched a dead person, they would be put outside the camp. If they had a leprous discharge they would be placed outside the camp. There were various reasons as to why Israelites would be deemed unclean and have to go outside the camp. The holy presence of God was to be protected. God protects his glory in his people.
As Israel became more like the other nations and desired their own fame in the world, they were often afflicted by God to bring them back to an acknowledgment of his holiness. God often used the other nations to do this. Israel found themselves at the receiving end of the power of Egypt, Assyria, Babylon, Persia, Greece, Rome and more. Throughout this time, God in his faithfulness kept his people in place looking to the Christ who would show all humanity what true holiness looks like in the worship of God
When we see God chastising Israel, even via the other nations, it is because God is holy and his people are to be holy. When we see God judging the other nations in total destruction, it is because they oppose God's holiness and have seduced his people into unholiness. God's judgment is not cruel. He does not commit hateful genocide. He is not unfair.
HE IS HOLY!