Every sin we commit is against God and must be confessed. In confession, we are not telling God anything he does not already know. In confession we are acknowledging we have sinned against God and stand in need of his pardon. We are affirming the truth about ourselves - that we are sinners - and the truth about God - that he is gracious. Our confession needs to be specific so that we can take full responsibility for what we have done wrong. Hearing ourselves itemise our sins prevents us from slipping into denial, which is easy to do. Furthermore, confession keeps us humble. When we confess our sins we have the assurance of a full pardon. John says, "If we confess our sins, he is faithful and just and will forgive us our sins and purify us from all unrighteousness." (1 John 1:9)
It is not sufficient to confess our sins only to God. There will be times when we must confess our sins to those we have sinned against. Jesus has strong words to say about confession that leads to reconciliation and makes true worship possible. "Therefore," he says, "if you are offering your gift at the altar and there remember that your brother has something against you, leave your gift there in front of the altar. First go and be reconciled to your brother; then come and offer your gift." (Matthew 5:23-24) First, go and be reconciled to the one you have sinned against. Resolve the problem. Confess your sin and seek forgiveness. When that has been accomplished, then, and only then, come to worship the Lord. Acceptable worship cannot exist where reconciliation does not exist, and reconciliation can only exist where there has been confession of sin. Jesus said, "If your brother sins, rebuke him, and if he repents, forgive him. If he sins against you seven times a day, and seven times comes back to you and says, 'I repent,' forgive him." (Luke 17:3-4) We must forgive those who sin against us and we must confess our sin to those we have sinned against. This has to be one of the most neglected practices among Christians. We sin against one another and never come and confess that sin and seek forgiveness from the one we have offended. Yet Jesus said we must not only seek God's forgiveness, but the forgiveness of the one we have sinned against. This type of confession reconciles people one with another.
James says, "Confess your sins to each other." (James 5:16) Not for one moment is James advocating that we engage in the indiscriminate confessing of our sins; to do so would not only be unwise, but would be unhelpful to some people who do not need to know our sins. The context of James's instruction is this: a Christian has sinned and, as a result, is afflicted by God. He needs to be healed. Recall that when David sinned he was affected physically (Psalm 32:3-4) and some Christians in Corinth suffered physically because of their sins. (1 Corinthians 11:30) The Christian who has sinned calls for the shepherds of the congregation, who have responsibility for the care of the flock, and confesses his sin, acknowledging that he has sinned against God and against the local church of which he is a member. He demonstrates a penitent spirit. The shepherds anoint him with oil, demonstrating their faith that God has forgiven him and will restore him to health.
Confession is good for the soul. It reconciles us to God and to those we have sinned against.