Why was Lot's wife punished for turning back?
In short: The text is not about a simple movement of the eyes, but about a heart turning back toward Sodom while God is drawing it out of death. Her glance reveals attachment to the world from which she was being saved.
The Orthodox nuance
In biblical language, turning back is not always merely a bodily movement. It is a direction of the heart. Lot's wife physically leaves Sodom, but she does not seem to have left it inwardly. This is why Christ Himself says, 'Remember Lot's wife,' when speaking of the person who must not cling to what is passing away.
We should not read the passage as if God were watching for a wrong reflex. The command not to look back is a call to complete detachment: leave death and do not negotiate with it. When the house is burning, you do not go back to admire the flames.
Spiritually, Sodom becomes an image of a life handed over to judgment. Lot's wife becomes the warning that one can walk toward salvation with the feet while keeping the heart turned toward what destroys us.
Sources
- Genesis 19:17 and 26
- Luke 17:32
- Luke 9:62
- Saint Maximus the Confessor (on passionate attachment)