Through the ministry of the Church
Well, Christ established the Church on the apostles, the first bishops giving them the power to bind or loose sin in this Sacrament — although in Christ’s quote no reference to a Sacrament is made.
Since Christ established the Church I have no problem with the forgiveness of sins especially since that forgiveness comes from GOD.
I realize that in their time the quote from James was appropriate, but I’ll take Christ’s words any old day. (And it’s in the Bible! Hallelujah!)
“Jesus said to them again, ‘Peace be with you. As the Father has sent me, even so I send you.’ And when he had said this, he breathed on them, and said to them, ‘Receive the Holy Spirit. If you forgive the sins of any, they are forgiven; if you retain the sins of any, they are retained.” (John 20:21-23)
I addressed the John passage already, in #17 of this thread.