The word "repent" means "to have another mind". To change the mind in consequence of of the inconvenience or injury done by past conduct. And this is what God requires of His people; to turn away from our carnal mind and have the mind of Christ.
The mind I have by default, in my natural state, is of self-righteousness; "I am rich, god increased with goods, and have need of nothing". I must completely turn away from this attitude and like Paul cry "O wretched man that I am! Who shall deliver me from the body of this death?" It is only after such a change of mind that I can confess, "I thank God through Jesus Christ our Lord." (Romans 7:24, 25).
Paul counsels us in Phillipians 2:5 that "LET THIS MIND BE IN YOU, WHICH WAS ALSO IN CHRIST JESUS." What mind is this? First of all, it is a mind that is totally emptied of self, entirely surrendered to God. Paul expounding on the mind of Christ declares, "But made himself of