Sometimes God's mercy isn't enough to save everyone.
I've spent a great deal of thought on Lot's story. From the reading of his story and the destruction of Sodom and Gomorrah, I believe Lot was caught unaware—like the proverbial frog in the boiling water—of the crescendoing hedonism around him.
He obviously knew enough to be afraid for the angels' safety if they slept out in the open (which was customary), but not enough to predict that his own home would be mobbed. Or that by the end of his encounter with the mob he’d be offering his own virgin daughters to the mob to placate their violent lusts!
Yet, even after Lot was told by the angels that destruction was coming, he dallied. When dawn came still he hesitated:
With the coming of dawn, the angels urged Lot, saying, “Hurry! Take your wife and your two daughters who are here, or you will be swept away when the city is punished.”
When he hesitated, the men grasped his hand and the hands of his wife and of his two daughters and led them safely out of the city, for the Lord was merciful to them. (Genesis 19:16-17)
Yet, God was merciful. The angels almost dragged them from the city. I find this interesting because Lot was exercising his free will by staying. Quite often, God mercifully saves us from ourselves, against our own protests.
Even then, this outpouring of God’s mercy wasn’t enough to save Lot’s wife.
Note: Some Jewish traditions teach that when she looked back, she saw the Shekinah glory of God as He moved to destroy the two cities. Since no one can see God and live, she was destroyed as well.
Even with all the mercy God showed: protecting them from the mob, allowing them time, dragging them from the city only moments before its destruction, even allowing them to flee to a small outlying city He said He’d spare (which, it seems, was too close for Lot's comfort after all)—it was not enough to save them all. This is true in our own lives, mercy only goes so far: we have to accept the mercy of the God who is our Salvation.
Instead of returning to Abraham, Lot leaves the small outlying city and lives in the mountains, begetting by drunken incest two people-groups who were thorns in the sides of the Israelites for a very, very long time. These were the Ammonites and Moabites.
But this is not the end of Lot’s story.
Though Christ is descended through the line of Judah, he is also descended from Ruth, who married Obed, the grandfather of King David. Ruth was a Moabitess who chose the way of the Lord instead of the gods of her own people.
There is a special ribbon of redemption woven in the line of Christ and Ruth's story is one of the threads. Blessed is the God who redeems and saves.
Sometimes the mercy of God drags us kicking and screaming from our own destruction. Sometimes the mercy of God cannot save everyone. Always the mercy of God has a plan to redeem and save.
Grace gives us ample chances.