The main point here in the record of Sodom's destruction is that God-the same God who has set in motion a plan to save people of every nation through Abraham's offspring-is a perfectly just judge of sinners. God judges justly. Further, as Jesus and his apostles taught, God's judgment on Sodom is the normal way God's judgment works- it's not an unusual judgment for unusually bad people. So, why hasn't what God did to Sodom been more common to other cities throughout history- It's God's sheer mercy. It's not because we're fundamentally better.