Genesis 19:26

On account of his hospitality and godliness, Lot was saved out of Sodom when all the country round was punished by means of fire and brimstone, the Lord thus making it manifest that He does not forsake those that hope in Him, but gives up such as depart from Him to punishment and torture. [Genesis 19:15-26, 2 Peter 2:6-9] For Lot's wife, who went forth with him, being of a different mind from himself, and not continuing in agreement with him [as to the command which had been given them], was made an example of, so as to be a pillar of salt unto this day. This was done that all might know that those who are of a double mind, and who distrust the power of God, bring down judgment on themselves and become a sign to all succeeding generations.

For God looks closely at the actual inner purpose, as when Lot’s wife was the only one to turn of her own free will toward the wickedness of the world. He left her insensible, giving her the likeness of a pillar of salt and leaving her without the power of forward movement, a statue, yet not one without a useful message but one intended to season and salt the person capable of spiritual perception.

But let us return to Lot, who, fleeing the destruction of Sodom with his wife and daughters after he had received the command from the angels to not look back, was proceeding to Zoar. But his wife became negligent of the command. “She looked back”; she violated the imposed law; “she became a little statue of salt.” Do we think there was so much evil in this transgression, that the woman, because she looked behind her, incurred the destruction that she appeared to be fleeing by divine favor? For what great crime was it, if the concerned mind of the woman looked backward whence she was being terrified by the excessive crackling of the flames?But because “the law is spiritual” and the things that happened to the ancients “happened figuratively,” let us see if perhaps Lot, who did not look back, is not the rational understanding and the courageous soul, and his wife here represents the flesh. For it is the flesh which always looks to vices; when the soul is proceeding to salvation, the flesh looks backward and seeks after pleasures. For concerning that the Lord also said, “No man putting his hand to the plow and looking back is fit for the kingdom of God.” And he adds, “Remember Lot’s wife.” But the fact that “she became a little statue of salt” appears to be an open indication of her folly. For salt represents the prudence which she lacked.
Lot therefore pushed on to Zoar. After he had gained strength there for a while, which he could not have in Sodom, he ascended the mountain and dwelt there, as the Scripture says, “he and his two daughters with him.”

And his wife, looking back, was turned into a pillar of salt. This indeed must be believed to have happened literally. Finally, Josephus reports that even up to his time the same pillar of salt had endured at the gates of the same city. And indeed, the wife, out of fear due to her feminine frailty at the sudden clamoring of the perishing and the crashing of the flames falling from the sky, looked back; but it nonetheless holds their figure in this infirmity, who, once renouncing the world and beginning the arduous journey of virtues, suddenly return with an unstable and almost feminine heart to the desires of the world they had forsaken; about whom the apostle Peter says: "It would have been better for them not to have known the way of righteousness, than after knowing it to turn back from the holy commandment delivered to them" (2 Peter 2:21); as, conversely, Lot, who left behind everything he possessed that was destined to perish with the sinners, suggests those who truly renounce the world, and regret not their renunciation; those whom also the blessed Noah, who left behind all his possessions to be destroyed by the floods with the reprobates, just as [Lot] did with the fire, clearly denotes; but the fact that the wife of Lot, when she turned away from the path which the Lord showed, perished and was turned into a pillar of salt; aptly signifies that those who deviate from the way of truth by returning to sins perish in their own depravity; yet by the example of their perdition they leave behind, as it were, a seasoning of wisdom for others, so that those remembering their destruction may guard themselves more cautiously and circumspectly in the purpose of righteousness they have taken up. Finally, the Lord, warning the faithful not to abandon the path of faith they have begun, employs for them, as it were, a rock of salt that they may more sweetly savor His words, when He says among other things: "Remember Lot's wife" (Luke 17:32). Therefore, anyone who desires to escape the fire of vices, which is the final judgment, must forget what is past and always strive towards the joys of divine promise that lie ahead.