I've seen that for many of those people it's not a matter of being right or wrong but a moral battle of good vs. evil. Heretics are to be purged, not discussed with.

Being honest I think religion is kinda hard-wired into the human brain and if it isn't the mystique kind like with Jesus or Allah then it (d)evolves into this kind of agno-atheistic fanaticism where some flavor of the year "problem" appears that these people obsess with. And this is coming from a long time atheist btw.