Why? God works His miracles in answer to our faith. For example, in the gospel of Matthew is narrated the cure of the Roman centurion’s servant who was paralyzed. This was how the gospel put it. After Jesus observed the faith of the centurion, He told him: “Go back then; you have believed, so let this be done for you.” And the servant was cured at that moment. (cf. Mt. 8:13).
Even while still on earth, our faith can be a source of grace and change. Jesus refers to that when He commented after curing or forgiving a person – “Your faith has been your salvation” (cf. Mt. 9:22, Mk. 5:34, Lk. 7:50). This is one basic point in our religion that we realize its teachings and sacraments are a source of righteous deeds. St. Paul described it this way: “I am not ashamed of the Good News (Gospel): It is the power of God saving all who have faith…..as scripture says: “The upright man finds life through faith” ( Rom. 1:16). Many skeptics want to deny this astounding effect of God’s marvels and miracles that comes from faith in Jesus Christ. But much of this is verified and documented historically, especially in the lives of saints and the very historical evolution of the Catholic Church amid all the trials and persecutions in the past and present. That is what precisely Jesus refers to when He talks about the forgiveness of sins. It means a change in persons and personalities for a better life of love and faithfulness to God. “So you see how it is written that the Christ would suffer and on the third day rise from the dead, and that, in his name, repentance for the forgiveness of sins would be preached to all the nations, beginning from Jerusalem . You are witnesses to this” (Lk. 24:46-48).