People who go on shooting sprees are by definition off-the-chain. It's not really helpful to speculate on their motivations, except to note that usually they are acting out fantasies that they have nursed for a long time.
Since some people appear to be a little dense, let's be clear: The idea that a spree killer would have views and an outlook on life identical to a relatively normal person in the cultural environment that surrounds them is absurd. There is something wrong with their heads.
Attempts to use them as poster children to indict whole groups of people you dislike by saying that this violence is inherent to the group--that they are all inherently murderous killers--will thus end up in failure.
There may be a line that can be drawn between a group's rhetoric and the actions of an antisocial killer, but it certainly won't be a straight line. Life is more complicated than that.
@John_Scotus i like this thread
Could it be that certain political or religious leaders may have created an atmosphere that encouraged them to act out in their fantasies? Certainly. But it would be surprising to find any consistency or logic in the beliefs of someone who just whacked a group of people.