I think any educated person should learn to accept joking as part of life. As in making cartoons of public figures we all hold dear or despise. And this also includes religion. Sadly we don´t see much from the catholic world and their problem with men perverting on young ones. Is it to much of a loaded subject to make a drawing out of it?
But in this case to hold a cartoon contest I would tend to believe they only did it with ill intentions. As in the same spirit having neo-nazis in a drawing contest of the the jew.
It´s all about the context. If Charlie Hebdo decided for some reason to have a contest with an end plan of finding future cartoonist for their magazine, I would be much more tolerant in their decision to do so.