Why confess sin? Is it so we can get rewarded by God? A little extra grace or material good for our troubles, maybe. Maybe, if we make a good confession, we can earn forgiveness? But, how much sin must we confess before we get what's coming to us? Which sins does God want us to focus on? What about other peoples' sin? Do we have to account for how they've interrupted our life and pushed us into sin? Then there's the fact that it's not in our power to know and number all our sins. In fact, the only sins we can know, according to St. Paul, are the ones that bother us most. You have your pet sins and I have mine, and what you call evil I call inane, so who's to judge? Only God knows and sees our every sin. That's why only God can ultimately judge sin.
Now, the purpose, the aim and goal of confession, is comfort. God commands us to confess so that we can be forgiven and comforted. Jesus especially intends for those of us who struggle with sin that we confess so the hideous weight of shame and guilt can be lifted off us and we may go about our life in peace.
We speak our confession of sin then God speaks to us His confession of forgiveness. All of confession and forgiveness is rolled up in God's Word. He speaks to us, "You the sinner." We answer, "Yes, me the sinner." He says, "You are forgiven in Jesus much." We say, "Amen." That's the way of confession and forgiveness with our heavenly Father.
In fact, there's no other way God does His business of forgiving us. Or maybe we imagine God does His forgetting of sin another way? Maybe we think we can forgive ourselves, or that family or friends can give us God's forgiveness in their own words? Maybe if we offer a blood sacrifice, or a sacrifice of our time, money and talents? No. That won't work. Our sacrifices don't have any teeth, no traction to them. Our sacrifices are not the way of forgiveness with God.
In the same way that we can't believe Jesus is Savior unless God sends us a preacher, in the same way there's no way we can know peace or comfort unless He sends us a preacher we can confess to, who will then forgive us in God's Name: Father, Son, and Holy Spirit.
So, we should always hold to this truth, that God doesn't want to deal with us in any other way than through His Word that's spoken to us by a preacher. Sure, the devil will try to confuse us. He will tell us we can find forgiveness apart from God's Word. But that's just not going to work out for us in the end. We can't forgive ourselves one time for all time AND forget our sin, no one else can either, and no amount of blood, sweat, or tears will give us a clean conscience.
Just as God spoke to Moses from a burning bush, to Balaam from the mouth of an ass, and Jesus wasn't conceived apart from the word of the archangel Gabriel, God's Word comes through a preacher He's sent to speak to us His good news, that on account of Jesus' suffering and bloody death all our sin is forgiven, forgotten, no longer remembered by our heavenly Father.
This Word from God that forgives us also makes us holy at the same time. The Holy Spirit is at work in His Word. It's not just plain words spoken to us by a preacher. It's God's Word and Spirit speaking to us through an instrument. Just as a musician breathes into a trumpet and it makes a beautiful sound, in the same way God's Word and Spirit breathe out a beautiful sound on us through His instrument, a preacher.
That's why the Church has always made such a big deal about confession. Confession isn't a pastor hunting up sins in order to trap us, condemn us, and throw us out of the church until we change our ways, get better, improve our life, and so on. Confession is done in Christian freedom, because we are free in Christ Jesus to confess and be forgiven. In fact, any preacher who hears our confession and doesn't immediately declare to us the entire forgiveness of all our sin for Christ's sake isn't from God. God's preachers are His instruments of forgiveness. All from Him to us, for us, for Jesus' sake. His blood covers our whole confession today and always.