This is a digital copy of Caravaggio's "The Incredulity of Thomas" that I found on Wikipedia.
When I look at the face of Thomas, it seems to me that Caravaggio is mocking him for wanting "hands on" proof of the real presence of the Risen Jesus.
I have always found the phrase "Doubting Thomas" to be judgmental, and loaded with the implication that it is wrong to be possessed of questions or doubt.
In my sermon I made the connection between the "bad rap" that doubt has received, and the harm that has been cause when the Christian church has failed to be humble- and has assumed that it had the exclusive franchise on truth. Alongside our history of spreading the gospel around the world, and doing good works in God's name, we have a darker history of managing to find some category or group of people to actively exclude, wherever we have gone.
Thomas, who is literally poking around, seeking the truth of things, may be for us not only the patron saint of "doubters", but also of all those who did not want to be left out.