John Henry Newman on the weakness of Thomas’s faith as a blessing for Christians seeking Christ:
“We must not suppose that St. Thomas differed greatly from the other apostles. They all, more or less, mistrusted Christ’s promises when they saw him led away to be crucified. When he was buried, their hopes were buried with him; and when the news was brought them, that he was risen again, they all disbelieved it. On his appearing to them, he “upbraided them with their unbelief and hardness of heart.” (Mark 16:14)… Thomas was convinced latest, because he saw Christ latest. On the other hand, it is certain that, though he disbelieved the good news of Christ’s resurrection at first, he was no cold-hearted follower of his Lord, as appears from his conduct on a previous occasion, when he expressed a desire to share danger, and to suffer with him…: “Let us also go, that we may die with him.” (Jn 11:16)… It was at the instance of Thomas that they hazarded their lives with their Lord.
“St. Thomas then loved his Master, as became an apostle, and was devoted to his service; but when he saw him crucified, his faith failed for a season with that of the rest… and more than the rest. His standing out alone, not against one witness only, but against his ten fellow disciples, besides Mary Magdalene and the other women is evidence of this… He seems to have required some sensible insight into the unseen state, some infallible sign from heaven, a ladder of angels like Jacob’s (Gn 28:12), which would remove anxiety by showing him the end of the journey at the time he set out. Some such secret craving after certainty beset him. And a like desire arose within him on the news of Christ’s resurrection.
“While our Saviour allowed Thomas his wish and satisfied his senses that he was really alive, he accompanied the permission with a rebuke: “Because thou hast seen me, thou hast believed: blessed are they that have not seen, and yet have believed.”… All his disciples minister to him even in their weaknesses, that so he may convert them into instruction and comfort for his Church.”