Terrorist are Muslim or are they?You decide

First sorry if the title is offensive to some viewers I'm not Muslim, I'm Mormon.But in class today we had a Muslim speaker and I brought up a question that would make a interesting topic. I found out that terrorists are considered Muslim because they believe in Allah but most of the other things they don't believe in. Is this fair that because they believe in some things we judge the people who really believe in it. I'm not saying terrorist don't believe in Allah if I did I be laying in the street in cold blood.I'm saying they have different opinions so judge them different not the same but differently.