Question: "Do we need to confess our sins to those we have sinned against?"
Answer: We know we are to confess our sins to God, but many Christians wonder whether we need to confess to those we have sinned against. Do we need to tell the person we’ve sinned against that we’re sorry? “Walking in the light” (1 John 1:7) means that we are living in obedience to God’s commandments. In the same verse, we have references to forgiveness through Christ and “fellowship one with another.” So, there is a connection between having a “clean slate” and our relationship with other people.
Every sin is ultimately committed against God (Psalm 51:4). The Bible consistently emphasizes our need to confess our sins to Him (Psalm 41:4; 130:4; Acts 8:22; 1 John 1:9). As for the confession of our sins to people, the Bible gives no blanket command. We are told many times to confess our sins to the Lord, but the only direct command to confess to someone else is in the context of church elders praying on behalf of the sick (James 5:16).
This does not mean that we are never to seek another person’s forgiveness. The Bible gives examples of confession to other people. One is Joseph’s brothers asking for his forgiveness in Genesis 50:17-18. And person-to-person confession is implied in such passages as Luke 17:3-4; Ephesians 4:32; and Colossians 3:13.
The principles here seem to be 1) We should seek forgiveness from the Lord for every sin. He desires “truth in the inward parts” (Psalm 51:6). 2) If our relationship with the Lord is right, then our relationships with other people will fall in line. We will treat others graciously, with justice and honesty (Psalm 15). To sin against someone and not attempt to make it right would be unthinkable. 3) The extent of the apology for a sin should match the extent of the impact of the sin. In other words, we should seek forgiveness from whoever was directly involved in order to ensure healing.
For example, if a man looks with lust at a woman, he should immediately confess the sin to the Lord. It would not be needed or appropriate to confess that sin to the woman. That sin is between the man and the Lord. However, if a man breaks a promise, or does something that directly impacts the woman, he must confess to her and seek her forgiveness. If a sin involves a large number of people, such as a church, a man or woman must then extend the confession to the members of the church. So the confession and apology should match the impact. Those impacted by the sin should hear the confession.
While our forgiveness with God is not dependent on our confessing our sins to others and/or their forgiving us, God does call us to be honest and forthcoming with others regarding our failings, especially when our mistakes involve them. When we have offended, hurt, or sinned against others, we should seek to offer a sincere apology and confession and ask for forgiveness. Whether the forgiveness is granted is up to those who were confessed to. Our responsibility is to genuinely repent, confess the sin, and ask for forgiveness.