Unhelpful Questions: Religious Terror

Reader Corey pointed us to this poll which shows us that (among other things) Americans are twice as prone to consider a terrorist (who claims a religion) to be "of that religion" if they are Muslim, than if they are Christian.


(The wording, for the record, is this: "When people claim to be Muslim and commit acts of violence in the name of Islam, do you believe they really are Muslim, or not?")

Wanted to discuss something about the question in general. 

It's of course being asked because as of late, every terror attack has been followed by a lot of running around making lots of  noise in order to show that the person claimed either one religion or another at the root of their attacks

The framing of the question is unhelpful because answering either a definitive "yes" or "no" just doesn't make sense: can anyone say that any given action (with perhaps a few religiously-prescribed rituals) is representative of that religion or not? Christianity and Islam are massive and diverse, with huge disagreement between different sects and practitioners as to what is and isn't the official or correct way of practicing the religion.

So when a terrorist claims to be representing a religion, and we're asked to determine whether their claim is "accurate," by what basis can we even answer such a question with a "yes" or "no?" 

Does it require a certain number of religious leaders of a certain rank to prescribe an action for it to become "of that religion?" Or a certain number of people believing it? Or a certain line in a particular religious text?

Perhaps more importantly, why do we feel like we as citizens need to have a clear answer to that question? If we thought one way or the other, would it change how we approached policy? 

Edited 12/2/2015 at 19:02 in order to clarify/narrow purpose and framing.