To ask a hypothetical question to opinionated dumb US public, what if the killer was a muslim.   There would be no "mentally ill",  no "deranged", no "sick individual", no "they guy needed help" but would be right away branded:

ISLAMIC TERRORIST

Knock ! Knock ! Islam is an expansionist ideology via force if necessary.

NOW !!! Back to your regularly schedule programming .

If the killer was Muslim he would probably have a political motivation, and yes he would be rightfully labeled an Islamic terrorist.
If he was a Muslim and had no political motivations I can assure you that our liberal main stream media would be pointing that out. He would most certainly not be labeled as a Muslim terrorist.

By the way, I see that you still have not mastered the definition of terrorist yet.

The Fort Hood shooter was called all those things and a Muslin too.  

Muslin is two steps up from Atheist anyways.