The Incredulity of Saint Thomas

It shows the episode that gave rise to the term "Doubting Thomas" which, formally known as the Incredulity of Thomas, had been frequently represented in Christian art since at least the 5th century, and used to make a variety of theological points. According to the Gospel of John, Thomas the Apostle missed one of Jesus's appearances to the Apostles after his resurrection, and said "Unless I see the nail marks in his hands and put my finger where the nails were, and put my hand into his side, I will not believe it." A week later, Jesus appeared and told Thomas to touch him and stop doubting. Then Jesus said, "Because you have seen me, you have believed; blessed are those who have not seen and yet have believed."

The painting shows in a demonstrative gesture how the doubting apostle puts his finger into Christ's side wound, the latter guiding his hand. The unbeliever is depicted like a peasant, dressed in a robe torn at the shoulder and with dirt under his fingernails. The composition of the picture is such that the viewer is directly involved in the event and feels the intensity of the process.

The light falling on Christ emphasizes his physicality and at the same time suggests his divinity and significance to the viewer. Caravaggio was a master of light and shadow, and he uses this chiaroscuro to create a narrative through line in this piece. The shadows (representing doubt) sweep over St. Thomas, but as he touches Christ he is drawn into the light.