Why do Orthodox Christians have to confess their sins to a priest?

As a Protestant, maybe you told somebody about a struggle, but you never had to go systematically to somebody and lay out all of your sins. That idea of uncovering my whole life was foreign to me. But then I started to realize that everything within the church was a safeguard against the individuality I was holding on to. The confession of sins was for my soul.

It wasn't so the priest knew what I was doing, and God already knew what I was doing. It was so that I could unburden my soul and receive forgiveness, the forgiveness Christ gives to the apostles when he tells them, I have given you power on earth to bind and loose sins. Whatever sins you bind on earth will be bound in heaven, and whatever you loose on earth will be loosed in heaven.

The things I was still experiencing in my own soul, still holding on to me, confession is to get rid of that. My own theological interpretation, which changed over time, was unreliable. I actually needed someone to tell me what to believe.