Our sins are forgiven, but we are not perfect. Paul said, Now I rejoice in my suffering for your sake, and in my flesh I am filling up which is lacking in the afflictions of Christ on behalf of His body which is the Church of which I am minister in accordance with God’s stewardship given to me to bring to completion for you the word of God...—Colossians 1:24 ff.
If our sins are forgiven, there’s nothing left to pay for.
If hey aren’t forgiven, we can’t pay for them except by death. We cannot save ourselves any how, any way.