Forgiving sin is not an issue of desire or will-power. It is an issue of authority. Most of us would not dare contest that Jesus walked in this authority. However, there is still a mentality in the church today that Jesus had no intentions of sharing this authority with His followers. In fact, the authority-less church is embraced because it relieves its members of responsibility. Do we have the power and responsibility to forgive the trespasses of others? Absolutely!
(Joh 20:22-23 MKJV)
(22) And when He had said this, He breathed on them and said to them, Receive the Holy Spirit.
(23) Of whomever sins you remit, they are remitted to them. Of whomever sins you retain, they are retained.
This is just another example of Jesus imparting power and authority to those called by His name. This was not Pentecost, for it was Pentecost that truly empowered Jesus-followers to undo the works of the devil. But this act of breathing upon His disciples was a basic establishment of their identity - ones who carried a core ability to forgive sin - or not to forgive sin. Again, this was not done to foster a God-complex upon Jesus' followers. It was done in order to create a heart of compassion, understanding, and responsibility in the Body of Christ, for we cannot and will not be 'like' Him if we cannot forgive as He forgives.