I kill ... I wound ... I will make mine arrows drunk with blood, and my sword shall devour flesh. Deuteronomy 32:39-42
You may have noticed that God, after his first mass murder, showed a bit of remorse for needlessly drowning pretty much everything on earth. He even promised to never "smite any more every thing living." (Genesis 8:21)
And he kept his promise, too (if you ignore the anti-Sodomite slaughter), for another ten chapters or so. But in the end, God couldn't resist the temptation to kill again.
Abraham tried to talk him out of it, though. He and God and a couple of God's friends had been hanging out all day together. But after getting their feet washed and eating a big meal, God and his friends decided it was time to go.
The LORD appeared unto him in the plains of Mamre: and he sat in the tent door in the heat of the day; And he lift up his eyes and looked, and, lo, three men stood by him: and when he saw them, he ran to meet them from the tent door, and bowed himself toward the ground, And said ... wash your feet, and rest yourselves under the tree ... And Abraham ran unto the herd, and fetched a calf ... And he took butter, and milk, and the calf which he had dressed, and set it before them ... and they did eat. Genesis 18:1-8
They were heading off toward Sodom and Abraham decided he'd better tag along.
The men rose up from thence, and looked toward Sodom: and Abraham went with them to bring them on the way. 18:16
As they were walking along, God said (to himself?), "Shall I hide from Abraham that thing which I do?"
The LORD said, Shall I hide from Abraham that thing which I do? 18:17
How's that for weird? God asks himself if he should tell Abraham what he is about to do (which is, of course, kill everyone in two cities). He doesn't know what to do. Is he afraid that Abe will talk him out of it? Or try to stop him? Or what? Or is he just embarrassed to be having bad thoughts again? But God finally snaps out of it and tells Abraham what he's up to. He has heard that the people in Sodom have sinned and he's decided to go to Sodom and see for himself.
The LORD said, Because the cry of Sodom and Gomorrah is great, and because their sin is very grievous; I will go down now, and see whether they have done altogether according to the cry of it, which is come unto me; and if not, I will know. 18:20-21
Abraham was on to him right away. He said, "Wilt thou also destroy the righteous with the wicked?"
Abraham drew near, and said, Wilt thou also destroy the righteous with the wicked? 18:23
God, who is in one of his moods, ignores him. So Abe starts to bargain. What if there are 50 good people in Sodom? Would you kill them, too? "Shall not the Judge of all the earth do right?"
Peradventure there be fifty righteous within the city: wilt thou also destroy and not spare the place for the fifty righteous that are therein? ... Shall not the Judge of all the earth do right? 18:24-25
God says if he can find 50 good citizens of Sodom, he won't kill everybody.
The LORD said, If I find in Sodom fifty righteous within the city, then I will spare all the place for their sakes. 18:26
So Abe tries 45, and God says he wouldn't kill everyone if there were 45.
Peradventure there shall lack five of the fifty righteous: wilt thou destroy all the city for lack of five? And he said, If I find there forty and five, I will not destroy it. 18:28
Abe keeps going this way (knowing that God is a tad slow). How about 40? 30? 20? 10? And each time God answers the same way: If he can find a few good men (well ten, anyway), he won't kill the whole city.
He said, Oh let not the LORD be angry, and I will speak yet but this once: Peradventure ten shall be found there. And he said, I will not destroy it for ten's sake. 18:32
And then God just takes off and Abraham goes home.
The LORD went his way, as soon as he had left communing with Abraham: and Abraham returned unto his place. 18:33
But God's two friends (they're called angels now) keep going to Sodom. Lot invites them in and gives them the usual God treatment (washes their feet and feeds them).
There came two angels to Sodom at even ... and Lot seeing them rose up to meet them; and he bowed himself with his face toward the ground; And he said, Behold now, my lords, turn in, I pray you, into your servant's house, and tarry all night, and wash your feet, and ye shall rise up early, and go on your ways. And they said, Nay; but we will abide in the street all night. And he pressed upon them greatly; and they turned in unto him, and entered into his house; and he made them a feast, and did bake unleavened bread, and they did eat. 19:1-3
Then a strange thing happened. (Strange things often happen in the Bible.) Every man in the city of Sodom came to Lot's house and demanded to have sex with Lot's two angel friends.
The men of Sodom, compassed the house round, both old and young, all the people from every quarter: And they called unto Lot, and said unto him, Where are the men which came in to thee this night? bring them out unto us, that we may know them. 19:4-5
Man, those must have been some good-looking angels! Lot's response was to protect the angels (who you'd think could take care of themselves) by offering the sex-crazed mob his two virgin daughters instead.
Behold now, I have two daughters which have not known man; let me, I pray you, bring them out unto you, and do ye to them as is good in your eyes. 19:8
[This is a man, by the way, whom the Bible calls "just and righteous" in 2 Peter 2:7-8. A few verses later he will get drunk and impregnate both his virgin daughters (see Genesis 19:30-38), but that's another lovely Bible story.]
As it turns out, though, there is no time for Lot to make good on his kind offer because God is getting ready to commit another mass murder. The angels strike the Sodomites blind, and tell Lot, his virgin daughters (and their husbands!), and his wife to flee.
But the men ... smote the men that were at the door of the house with blindness ... And the men said unto Lot, Hast thou here any besides? son in law, and thy sons, and thy daughters, and whatsoever thou hast in the city, bring them out of this place: For we will destroy this place ... the LORD hath sent us to destroy it. 19:10-13
And then all hell breaks loose.
The LORD rained upon Sodom and upon Gomorrah brimstone and fire from the LORD out of heaven. 19:24
OK, so that's it. That is God's second mass murder.
But how many people did God smash and burn to death in Sodom and Gomorrah? Well, I, of course, have no idea. I don't think any of this actually happened. But I'll guess 2000, 1000 from each city.