The depravity of the inhabitants of Sodom was so monstrous that it was beyond all hope of reformation. God decreed that the city needed to be destroyed. Angels were sent to save Lot’s family — not in their own merit, but for Abraham’s sake. The rescuers warned Lot and his family not to watch as the city was leveled. Unfortunately, Lot’s wife did look back, and was turned into a pillar of salt.
Why did Lot’s wife need to pay such a heavy price for her curiosity? Why wasn’t Lot’s family allowed to observe the destruction?
Just as there are levels in righteousness, so too there are levels in wickedness. Some unscrupulous individuals are in fact good people who came under the influence of unprincipled friends and a milieu of crime and corruption. These misguided individuals are receptive to change. If they witness the just punishment of the wicked, their innate goodness is awakened, and they are encouraged to return to the proper path.
On the other hand, some people are so incorrigibly evil — psychopaths and hardened criminals, for example — that they cannot be helped. The only thing restraining their evil excesses is fear of punishment. This was the state of the residents of Sodom, who were perfectly comfortable with their evil ways.
When the incorrigibly wicked witness the downfall of evil, it has the reverse effect on them. It actually reduces the fear that holds their vices in check, since imagined punishment is more frightening than the real thing. When they observe havoc and devastation, they become less inhibited and pose an even greater menace to society.
Lot’s family did not deserve to be saved. They lacked moral resolve, and were drawn to the malevolent and degenerate ways of their evil neighbors. Only fear of Divine retribution kept their immoral tendencies in check.
Lot’s family was commanded not to watch the destruction, in order to maintain their fear of God’s justice. This fear was the only means by which they could escape the influence of Sodom. When Lot’s wife willfully looked back, she lost some of her fear of judgment. She became like the other residents of Sodom, who were destroyed because they were irredeemably corrupt. Lot’s wife shared the severe punishment of her fellow Sodomites — “brimstone and salt.” She too was turned into an inert pillar of salt, an apt symbol of her immutable and irreparable state of evil.
(Adapted from Ein Eyah vol. II, p. 250)