your greatest sin

is not the abortion that you've asked forgiveness for,

or the adultery, 

or ... whatever it is that you did in your life in the past that you're ashamed of, that keeps hounding you. 

your greatest sin is not that your greatest sin is not believing God's Word when God says you're forgiven. 

your greatest sin is ... unbelief.

you want to repent of something, friend? 

stop repenting of sins that you're already repented of, and repent of your unbelief.