I guess it depends on your life's experiences.
Down here, you can't throw a rock without hitting some "end times" religious whackjobs*. They are very open about their beliefs in "God, guns, and freedom." For them, naturally. Hell, Waco and the Branch Davidians wasn't that long ago. So I find the idea of a militia wrapped up with religion to be a far more realistic and concerning plausible reality than some rando psychopath with a flair for soap opera level melodrama.
There are four large militia groups in Texas, alone.
Here's an example of one.
*A small bit of hyperbole. I wouldn't say they're on every corner but they're not rare, either.
"Just take a look around you, what do you see? Pain, suffering, and misery." -Black Sabbath, Killing Yourself to Live.