Doubting Thomas

Caravaggio, The Incredulity of Saint Thomas, 1602 (Wikipedia)

Today is Divine Mercy Sunday, and the Gospel is from Chapter 20 of the Gospel of John.  The painting here shows the moment at which Jesus confronts Thomas:

Jesus said to Thomas, "Let me have thy finger; see, here are my hands. Let me have thy hand; put it into my side. Cease thy doubting, and believe." Thomas answered, "Thou art my Lord and my God."

According to Edwin Aponte:

Known for his gritty realism, Caravaggio has Jesus grasping the hand of the apostle Thomas and thrusting it deep within the wound at his side, powerfully aligning Jesus' and St. Thomas' hands to form a lance. St. Thomas' face expresses profound surprise as his finger thrusts deep into Jesus' wound. Perhaps, the surprise has to do with his unbelief. It could also be surprise at the realization that he, too, is also pierced. Indeed, St. Thomas appears to clutch his side as if he becomes aware of a wound at his side as well. And we who wince at this gritty depiction feel a wound at our side as well.