We would realize that a big change happened in Thomas – from an apostle who doubted in Christ’s resurrection, he went on to declare not only his belief in his Master’s resurrection but he also acknowledged Him to be God. His declaration: “My Lord and my God!” is a loaded expression.
What had happened? An encounter between Thomas and Jesus’ love had taken place. He encountered the loving Heart of Jesus when he put his hand on Christ’s wounded side.
When the soldier on calvary pierced Christ’s side, blood and water came out of the wound. In it the Church always saw the Sacraments which give her its vitality especially the Sacraments of Baptism and the Eucharist. Besides Jesus himself told us that out of the believer’s heart shall flow rivers of living water which is the Holy Spirit. Therefore when Thomas came face to face with the wounded side of Christ he realized that he has come face to face with the love of the Heart of Jesus for him.
He has encountered the wounded Heart of Jesus, wounded out of its love for humanity. It is the heart that has burdened itself with the sin of man. Because this is what love does: it suffers for others, and Thomas was in the presence of the wounded love. He understood that the suffering of this Sacred Heart is the result of man’s ingratitude. Thomas understood also that, in Jesus, he was in the presence of the Divine Mercy who became man.
It is this Divine Mercy that has taken upon itself the sin of humanity instead of punishing humanity for its transgressions. Because that is what the Divine Mercy does: it forgives, heals and renews man. This is what Thomas experienced in its presence and his heart became a heart full of love because he had experienced forgiveness, healing and renewal.
When Jesus appeared to the apostles the week before, he gave them his Holy Spirit, not as in Pentecost, but in a new way and for a specific reason: so that their heart will be like his: a forgiving and loving heart. He gave them the mission of changing man’s heart and make it a heart like the Heart of Jesus: an understanding heart, a heart full of mercy and love for all.