CAIN'S ENVY
Cain is displaying an attitude that many non-Christians have about Christians. There is often indignation from those who don’t believe they deserve to be in God’s favor, derogatory statements like, "Christians are a bunch of do-gooders, hypocrites etc." Often this reflects their deep wish to be reconciled and accepted by God, but instead they have anger toward those who are.
So often we exhibit anger instead of repentance when we are accused of doing something wrong. Very often after a time has passed, the anger subsides and guilt and sorrow take its place. Once again there is a lesson here to just confess and repent when we are caught, so that we can avoid long-term inner turmoil, though we may still have to deal with the consequences of our actions.