See... God and Satan were sitting around talking.

Satan: "God, these humans only love you because you give them good stuff."
God: "No they don't."
Satan: "Prove it."
God: "Ok, you see Lot over there?"
Satan: "Yep"
God: "We can both agree that he has a lot of stuff and a big family full of love and stuff... right?"
Satan: "Yeah..."
God: "He also loves me right?"
Satan: "Yeah..."
God: "Ok... you can do whatever you want to Lot and his family... the only thing you can't do is kill Lot. We'll see if he still loves me afterwards"
Satan: "Seriously?"
God: "Sure... go for it."
Satan: "Woot!"

Satan goes off and kills his entire family, kills off all his livestocks... gives Lots some crazy disease.

But Lot prays to God, "I still love ya Man!"

God wins the bet.