Both sides have to repent and change. But forgiveness takes only one person, because forgiveness is something we do in our hearts. God forgave the world, but the whole world is not reconciled to him. Although he may have forgiven all people, all people have not owned their sin and appropriated his forgiveness. That would be reconciliation.
Forgiveness takes one, reconciliation takes two.
Forgiveness has to do with the past, reconciliation has to do with the future. That is why it is so powerful. It is God's purpose through Christ here on earth. Unless noted otherwise, materials on this website are copyrighted by the Worldwide Church of God .