Christ’s death made possible and available the forgiveness of the sins of everyone in the world, but this forgiveness is effective only to whosoever believeth (John:5:24Verily, verily, I say unto you, He that heareth my word, and believeth on him that sent me, hath everlasting life, and shall not come into condemnation; but is passed from death unto life.
See All... [1]; 6:40; 11:25–26). When saved persons ask for the forgiveness of a sin today that was forgiven centuries ago on the Cross, they are essentially recognizing the availability of forgiveness and accepting that forgiveness as 1 John:1:9If we confess our sins, he is faithful and just to forgive us our sins, and to cleanse us from all unrighteousness.
See All... [2] tells them to do. Asking the Lord for forgiveness is a natural outflowing of confession—evidence of our confidence that indeed it is available and received. —TBC

"Verily, verily, I say unto you, He that heareth my word, and believeth on him that sent me, hath everlasting life, and shall not come into condemnation; but is passed from death unto life."

—John:5:24Verily, verily, I say unto you, He that heareth my word, and believeth on him that sent me, hath everlasting life, and shall not come into condemnation; but is passed from death unto life.
See All... [1]