This is some powerful text from 1 John, it really highlites the need for self assessment. The walk in darkness indicates a continuous walking in sin and disobedience to God's word. Someone that calls themselves a Christian and goes through their lives always lying and cheating and completely consumed with themselves will probably be very surprised come judgement time.
We will not be perfect on this side of Heaven, but if we are believers we should feel remorse and guilt whenever we do something that God has told us is sin. The forgiven sinner is fast to confess, agree with God, that they messed up in order to restore fellowship with God and one another.
I pray you have a great week,
Sent from my iPad