I'm more than happy to join in the widespread condemnation of Hamline for this incident, where they fired a professor for showing an image of a medieval Muslim painting of Muhammad to her class, because some Muslims object to it on religious grounds.
I would merely add that Muslims are far from the only ones who object to some types of artwork for religious reasons. There is a long history of conflict over such things within Christianity, as well. Early Protestants broke with the Catholic Church in part because of their opposition to Church's use of images of saints and the like. Today, many theologically conservative Christians object to sexually explicit art work, depictions of Christ that violate their beliefs (remember the "Piss Christ" controversy?), and so on.
So if this policy (barring the classroom use of images that might offend religious believers) is consistently applied, professors could be fired for showing students a wide range of Western artwork, as well.