Why is it important to make a good Confession, formally, to a Priest? Why should we have to tell anyone how we’ve sinned? Well, there’s accountability, for one thing:
When you make your confession to a priest, you acknowledge that you have sinned not only against God, but against every single other Christian because by your sin, you have lessened the universal witness of every single Christian. You have given the non-believer the excuse that “All Christians are hypocrites.” When you go to Confession you acknowledge that you have caused every Christian to suffer by your sins. —Dr. Taylor Marshall, Canterbury Tales
The book of James speaks of Confession in general terms:
“Confess therefore your sins one to another: and pray one for another, that you may be saved. For the continual prayer of a just man availeth much.” –James 5:16
As for Absolution, when Jesus ordained His apostles, He instructed them to forgive sins on His behalf:
” He said therefore to them again: Peace be to you. As the Father hath sent me, I also send you.When he had said this, he breathed on them; and he said to them: Receive ye the Holy Ghost. Whose sins you shall forgive, they are forgiven them; and whose sins you shall retain, they are retained.” –John 20:21-23
“As the Father hath sent me, I also send you.” Right there. Jesus sends the Apostles out as His representatives on earth. Not to skip to another topic entirely, but it also comes down to who a Priest is, an ambassador. When I confess my sins to the Priest, he is standing in on behalf of Jesus Christ, and when he gives me Absolution, he is doing so on behalf of Jesus Christ.
The early church confessed openly to each other in the congregation, according to the Didache. This was the first means of confession.
In the congregation thou shalt confess thy transgressions, and thou shalt not betake thyself to prayer with an evil conscience. This is the way of life. –Didache 4:14
They did this every week, on the Lord’s day.
“On the Lord’s Day of the Lord come together, break bread and hold Eucharist, after confessing your transgressions that your offering may be pure;” –Didache 14:1
Over time, it evolved into the practice we know today, where Confession is heard only by a Priest, which, really makes far more sense than telling the whole of the congregation. Especially since Jesus gave authority to forgive sins to His Apostles, not all mankind, so only the Apostles could give Absolution.
There are, of course, far deeper and more personal reasons to make a good Confession. More on that very soon.