Everyone has right to live his life by his own opinion.. opinion varies among people but this is not right you attack on someone's religion's or his believes...
So you have no problems with what ISIS is doing then? Their religious belief is to go round killing people.
If we followed your advice, we would not be allowed to criticise them.
ISIS and Atheists both like to kill people, cutting their throats or go to school and start shooting. Christians never do that. Based on empiric facts.