There's a simple fact that Kuffar, Mushrikeen, atheists need to learn is that you can't be a Muslim if you don't love Prophet Muhammad (saww) more than your mother, father, sons and yourself.
If someone was to mock our mother and make her cartoons, what do you think would be my or anyone's reaction? Even the Kuffar and Mushrik understand the love for mother.
We love Prophet Muhammad (saww) more than our mother. What do you think the reaction of Muslims would be when you think bad thoughts about such a perfect person (saww)?