What does the Bible say about genocide?
The biblical conquest of the “promised land” is a horrific blend of genocide, slavery, rape, and pedophilia COMMANDED BY “God”. (To get the context, see Numbers, Deuteronomy, and Joshua for starters.)
Sometimes God's command is: Kill everyone, including children and babies. (see footnote 1)
Sometimes God's command is: Offer peace to the people whose land you are invading. If they don’t
accept it, kill all the men and enjoy the women and children for yourselves. If they accept “peace”, enslave them all. (Deuteronomy 20:10-18)
And sometimes God's command is: Kill all the men, females who have already had sex with a man, and all
male children, and then take for yourselves all the female children who have not yet had sex. (Numbers 31)
“When you go out to war...and you see among the captives a beautiful female (see footnote 2), and you desire to take her to be your wife, and you bring her home to your house, she shall shave her head and pare her nails. And she shall take off the clothes in which she was captured and shall remain in your house and lament her father and her mother a full month. After that you may 'go into her' and be her husband, and she shall be your wife.” This rape-marriage of a young girl (right after killing her entire family) is a sick Handmaid’s Tale scenario invented by God
(according to Deuteronomy 21:10-13).
As God introduced His idea of “cherem” (total annihilation/genocide) in His Holy Scriptures, it would have been exceedingly welcome for Him to also say “By the way, never do this again!”. Or even "ONLY do this when I specifically give you the command!" (although that wouldn't clear things up much because, in the Bible, it's easy for anyone to "hear God speaking to them"). But He doesn't. Instead He sets the precedent that His followers can implement His cherem whenever they see fit. In 2 Kings 10:18-30 Jehu, with no specific command from God, LIES to worshipers of another religion, telling them that he wants to worship with them. He gathers everyone from that religion throughout all of Israel. Then he worships with them and offers burnt offerings with them. And then he and his army kill every last one of them in their own place of worship. God did not specifically tell Jehu to do that, but God was very happy with Jehu and said “Because you have done well in carrying out what is right in my eyes, and have done to the house of Ahab according to all that was in my heart, your sons of the fourth generation shall sit on the throne of Israel”.
So, as any teacher can see, God gave people a perfect education in how to commit genocide. And it remains His command throughout Christian history (Matthew 5:17-19). Cherem was implemented in the Crusades of the Middle Ages (where Muslims were declared Amalekites) and in the great religious wars of the 16th, 17th, and 19th centuries (where both Catholics and Protestants each declared each other Amalekites to be completely annihilated) and often in Colonialist confrontations with "Indians"/Native Americans (It was considered a defiance against God to not kill as many Indians as possible).
Maybe in the Old Testament genocides, God is merely trying to educate humanity about His character. Maybe He is demonstrating how big of a deal it is when people don’t worship Him….. Well, for a timelessly perfect God, his Iron Age pedagogy did not age well. The absurdity of His approach is not even laughable. Can you imagine a parent saying to a child "Dear one, your siblings have disobeyed me. So I want you to kill your brothers and rape your sisters so that you all know how important this is to me.” Does this sound like the words of an omniscient God who is wiser than humans? Or does it sound perfectly consistent with the behavior of other Iron age tribal deities?
FOOTNOTES:
1. For example, in Deuteronomy 3, God orders “cherem”, total destruction, of 60 cities as the Israelites move into their promised land. He commands the killing of all men, women, and children (obviously including unborn babies). See also Joshua 6 and 1 Samuel 15. In Deuteronomy 7, God commands His people to exercise hatred and lack of pity as they kill all humanity in the land. In Deuteronomy 13:12-18, God gives people an ongoing mandate to implement cherem on entire cities whenever they hear rumors of (and then ask around to confirm) other religious activity. They are to carry out cherem, killing all humanity with the edge of the sword and then burning everybody. If people carry out these occasional genocides, God will be merciful and compassionate toward them. In Joshua 10, Joshua goes from city to city to city carrying out cherem, killing everything that breathed, just as the God of Israel commanded. These passages make cherem seem very open-ended, available at any time to anyone willing to “obey God”. It’s no wonder cherem has continued to be practiced throughout Christian history.
2. The Hebrew word here “Ishshah” can be translated wife, woman, or female. Most translations of this verse generously render it “woman”, but since God’s tendency is to strongly prefer young virgin girls (see Numbers 31), it’s more accurate to leave the translation more vaguely “female” or even "young girl".