Although Roman Catholic doctrine teaches the need to confess to a priest for absolution, the context of our passage makes clear the teaching of John: we must confess our sins to God first, for only He can forgive us and remove our fault. Other passages of Scripture teach us that on certain occasions, it is necessary to confess our guilt to those who have been harmed by our sins, so that the communion that has been interrupted by our error may be restored (Luke 15:21).
What all true believers experience in confessing their sins is that God is faithful and just to forgive us our sins and to cleanse us from all unrighteousness (1 John 1:9). The word “faithful” has to do with being trustworthy. Faithfulness or trustworthiness is one of God’s attributes. His fidelity consists in always fulfilling what He promises. God will fulfill His promises of forgiveness made to His people, promises that were sealed in the blood of Jesus (see 1:7), when we humbly confess our sins to Him. Thus, we know that the certainty of forgiveness is not a matter of feeling that we have been forgiven but of God’s being faithful to what He has promised. And He cannot fail (2 Tim. 2:13).
John further adds that “God is just” to forgive us our sins (1 John 1:9). The sacrificial death of Jesus is certainly the background to this statement. God will do what is right: He will forgive us and cleanse us from all evil, for Jesus Christ has already paid for our guilt.