"Notice this other interesting statement: "he is a man to whom the Lord will not impute sin, he will not reckon sin to him". What does that mean?". The man has committed sin, how then can he be a blessed man? The answer is that though he has sinned and is guilty of many sins, God will not put down sins to this man's account in His heavenly ledgers. He might do so, He has a perfect right to do so. He does not put them down in the account. He leaves them out. He has sent them away - He has covered them up. He has forgiven them!".
Dr Martyn Lloyd-Jones - "Romans 3:20 - 4:25: Atonement and Justification" - Banner of Truth Trust, Edinburgh (1971) - (p175).