Those in Christ are promised forgiveness of sin by confession in prayer.
1 John 1:7 But if we walk in the light as He is in the light, we have fellowship with one another, and the blood of Jesus Christ His Son cleanses us from all sin. 8 If we say that we have no sin, we deceive ourselves, and the truth is not in us. 9 If we confess our sins, He is faithful and just to forgive us our sins and to cleanse us from all unrighteousness.
We cannot live a sinless life – hence the clause in the ‘Lord’s prayer’:
Luke 11:4 And forgive us our sins, For we also forgive everyone who is indebted to us.
To be ‘in Christ’ and ‘walk in the light’ of his commandments we must:
If we do this we can be confident that our sins are forgiven by confession in prayer.
May I suggest that you read Your Share in God's Promises (Please click on the title)
I hope you find this helpful.