Thomas does not believe it when the other apostles tell him, “we have seen the Lord.” It isn’t enough for him that Jesus had foretold it, promised it: “on the third day I will rise.” He wants to see, he wants to put his hand in the place of the nails and in Jesus’s sign. And how does Jesus react? With patients: Jesus does not abandon Thomas in his stubborn unbelief. He does not close the door; he waits. Thomas acknowledges his own poverty, his little faith: “my Lord and my God!”, He responds to Jesus’s patience. He lets himself be enveloped by divine mercy. He is a new man, no longer an unbeliever, but a believer.
– Pope Francis, The Church of Mercy