Erhard Schoen, The Devil with a Bagpipe (c. 1535)

Two versions, the first has been altered with pen to add eyes to the Devil's stomach.

This image was used as a broadside by the "reformers" against the Roman Catholic Church. The lower right hand corner is where they would put messages of dissent before they posted these around the town. The image depicts the Devil playing a monk like a bagpipe, reinforcing the idea that monks were instruments of the Devil.
Being that Martin Luther was a monk, many believe that this is a caricature of him, however, "no such print is known with the addtion of a suitable anti Lutheran text" 1

1 German Renaissance Prints: 1490-1550 Guilia Bartrum pg. 95