I don't get it though, if it is clear in a religion that showing a picture of the prophet drawn by human hand is not allowed, why show the picture, especially when you have members of that religion in the class and local community. Talk about it sure, but why show it? Would mods allow the Charlie Hevbdo cartoons to be posted on this forum, given that I imagine there is a sizable muslim comunity here that would find the offensive?
It feels to me like saying to a class with some Jewish students let's eat some pork. There's nothing unhealthy about eating pork it's only banned in the Torah because pigs don't chew cud (An animal is allowed if it chews cud and has cloven hooves)
These religious rules may seem small and ridiculous to those who are not part of that religion, but are big deals for those that are.