Sin loves the rear-view mirror. It keeps you looking backward. And it often happens in two ways:
It can keep you in despair by reminding you of past sins; even though God says in Isaiah chapter 43 verse 25 that He is the One who blots out your transgressions and remembers your sins no more.
Further in chapter 44 verse 22 He says that He has swept away your offenses like a cloud and your sins like the morning mist.
In Micah chapter 7 verse 19 says that God will again have compassion on us and will tread our sins underfoot and hurl all our iniquities into the depths of the sea.
So by all means, avoid the backward look for your sins are forgiven and forgotten by God.
The other way in which the backward look works is more dangerous. In Luke chapter 17 verse 32 Jesus asks us to “Remember Lot’s wife!” The reference is to Genesis chapter 19 verse 26 where it is said that Lot’s wife looked back and became a pillar of salt.
When the Lord delivered Lot, his wife and two daughters from the destruction of Sodom and Gomorrah, He commanded them not to look back. Lot’s wife disobeyed this command.
At least one reason for her looking back was that the sinfulness of these cities had a strong hold in her heart. Though she had come out of these cities she must have cherished the worldliness that these cities provided. Even though she was out of these cities her heart was still in there.
It would be right to think that when she looked back and became a pillar of salt she retained the posture of the backward look! So beware, avoid cherishing past sins. Avoid the backward look!