Rather than viewing/interpreting this act as an example of religious radicalism I can see it as a form of sexual violence. Herein the perpetrator, because of an internal/psychological sense of sexual impotency, relied on a “penis extension” i.e an automatic weapon in order to (sexually) assault others. In this case these “others” i.e a homosexual community,were most likely seen by the perpetrator as a threat due to the fact that they openly were expressing feelings that the perpetrator had much hidden shame towards. He was possibly/probably a latent homosexual and most definitely a homophobe. But because of his impotency (not necessarily a physical dysfunction, but rather a psychological inadequacy) he made himself extra potent by way of incorporating a deadly weapon.
Perhaps if the FBI had looked into his sexual conflicts they might have been able to recognize this murderer before the crime was committed. Notable as well, is the fact that he did not really know much at all about the group of radicals he supposedly had espoused. Most likely this religious group was, to him, a “safe haven” wherein he could express (violently and murderously) his inner conflicts, and had nothing at all to do with religion.