I was just writing about that! First off, there is no military accepted standard definition of terrorist. In the case of the purple heart, the approving authority would make the call as to whether this qualified as an
international terrorist incident (note, the reg saying international, Hasan was an American). In general, a terrorist incident is one in which civilians are intentionally targetted to forward a political agenda. here is a great article on the subject and he makes a great point, which you also allude to, Bill.
http://www.informationclearinghouse.info/article23933.htm
We keep focusing on some religious aspect. First of all, the purple heart makes no distinction about religion, neither does the US Military. In fact, a terrorist attack, doesn't have any link to religion. Religion is simply a belief system held by the attacker, now, it may be the reason for the attack, but they are separate. If use religion as a standard, then many other incidents fall under this heading, meaning that the crusades were terrorist attacks, among many other attorcities committed in the name of religion.
I would say that you are right, when we talk about acting alone that really makes the difference. A terrorist, in general is workign toward a greater political goal mainly as a part of some larger organization or grouping of people, such as Al Quaeda.
Remember that most terrorists are not psychopaths. We may say that based on our cultural views, but these people come from a different culture. You have to realize that in their culture (therefore, their entire life and upbringing - if they were raised in an extremist sect), they are taught that killing infidels is good and you will be rewarded. I use the term psychopath loosely, without reference to an actual definition...it just seems to fit my needs, but I do think that he is mentally unbalanced in one way or another. A religious extremist that commits mass murder is in his right mind, it was a premeditated, thought out act, not the result of mental illness or imbalance. It was a result of what we Americans call a bad culture.