In Life Together, Dietrich Bonhoeffer provides a treatise on the virtues of confessing our sins to one another. The practice, he argues, is vital to the Christian life and adds tremendously to the fellowship of believers; for in confession, Christians admit to one another that they are sinners in need of grace, and they shine light on their sin, which desperately desires to stay hidden (or at least we seek to keep it so).
Confession benefits the Christian in many ways, according to Bonhoeffer. First, it reveals sin in order to sanctify the sinner. Second, it enhances the fellowship of believers because it highlights the fact that no Christian is the only one struggling with sin; we are all in a fierce spiritual battle, and we can encourage each other in the fight. Third, it uplifts the sinner, for the one hearing the confession is a sinner himself, and can deeply sympathize with the one confessing. (Of course, Christ, too, can sympathize with us, as He took on humanity in the Incarnation and thus experienced for Himself human weaknesses and lusts. See Hebrews 4:14-15. I am surprised that Bonhoeffer did not mention this.)
Bonhoeffer goes on to address some misconceptions and malpractices concerning confession. He starts with the point that confession to fellow sinners should be easier than confession to God, who is holy and pure and the just judge of all evil. Fellow sinners saved by grace are a blessing of God to Christians for help in the midst of sin, as co-strugglers. We can boldly approach God, who loves us as we are and forgives us by His grace; but we can approach fellow Christians even more boldly, as they have experienced temptation and sin themselves. Next, he warns against mere self-absolution in the private confession of our sins to God. (Are we just clearing the record for our own satisfaction?) Also, Bonhoeffer stresses that the one who hears confession ought to practice it himself -- because he may otherwise become overburdened or even power-struck with his knowledge. The one who hears confession must humble herself and commiserate with the fellow sinner. Last, those who confess must keep in mind the gravity of what they are doing; confession is a striving toward sanctification, not an empty act of piety or a mindless duty.
"Therefore, confess your sins to one another. . . ." -- James 5:16a