"The death we die as sinners in confession gives rise to new life. Something in fact has died--our social saint (more pernicious in some than others) as well as the power of the sin itself. But we become alive to Christ and his church as never before. We arise in Christ with the family of Christ. In the light of his resurrection, veils of shame, guilt and deception fall away, demons flee and sin's power begins to dissipate.
Forgiveness is the first expression of this resurrection power. Upon appearing to his disciples, the resurrected Christ sent out his disciples with the command to forgive sins. 'He breathed on them and said, "Receive the Holy Spirit. If you forgive anyone his sins, they are forgiven; if you do not forgive them, they are not forgiven"' (Jn 20:22-23). We as his disciples are thus imbued with his Spirit to proclaim forgiveness to those who confess sins. This is resurrection power, since the proclamation 'You are forgiven, in Jesus' name' resurrects a person from the death of the sin.
Assurance of forgiveness results from a priestly proclamation. The brother or sister who has heard our confession speaks the word of forgiveness. Without such a witness, we are prone to mumbling admissions of sin and absolving ourselves, neither of which can impart the power of new life to us. Only the forgiveness of God can. And this occurs with certainty through the priestly word of our brother or sister.
Bonhoeffer wrote, 'Who can give us the certainty that, in the confession and the forgiveness of our sins, we are not dealing with ourselves but with the living God? God gives us this certainty through our brother... The assurance of forgiveness becomes fully certain to me only when it is spoken by a brother in the name of God. Mutual, brotherly confession is given to us by God in order that we may be sure of divine forgiveness.'"
~Andrew Comiskey, Strength in Weakness: Overcoming Sexual and Relational Brokenness (Downers Grove, IL: InterVarsity Press, 2003), 101.
Quotation from Dietrich Bonhoeffer, Life Together, trans. John W. Doberstein (San Francisco: Harper & Row, 1954), 116-117.