I doubt that any criminal organization would actually hire this guy, but my point is that sometimes it does not take conflicting religions or philosophies to make someone do something like Sandy Hook, just someone who is "crazy", which I am defining as someone who would do something like this.
This makes me think about the causes of many larger conflicts in the world today. Us cold-war products tend to think that wars, insurrections and the like are normally ideological in nature; now I'm thinking that the period where that was true was a historical blip. Nowadays the phrase "sectarian violence" gets slapped on every conflict between people who are (at least nominally) of different belief systems, which ignores the fact that in many (most? nearly all?) cases the religion is less the motivation and more the label du jour for another flavor of identity politics. India's BJP, for instance, a so called "Hindu nationalist" party, has always struck me as being much less about the former and much more about the latter. Identity politics is crazy, pretty much by definition, but it's a very human craziness, one into which most of us fall in various ways and degrees. And identity politics itself can become the label for even simpler human vices such as greed. The military junta in Myanmar isn't about ideology, and the various warring factions in the DRC aren't about various flavors of nationalism. They're just a bunch of crooks.