They think fire and brimstone and eternal torment are what waits right after death. I think it was in John where we're told to be absent from the body is to be present with the lord... but that's just as I recall it.

What those people are doing is conflating "hell/sheol/the afterlife without God" and the Lake of Fire spoken of in The Revelation of John. In his vision, John sees the end of time, the end of existence, when all that God Created is judged, and when the accuser, his demons, and all those not found in the Lamb's Book of Life are put into the Lake of Fire for eternity.

The question, then, is John's vision a literal reality? Most of the rest of his revelation is given is terms that would make sense to a dreaming mind, or that could be allegorical/metaphoric. For that reason, I'm not sure the Lake of Fire with eternal torment is literally what waits for those who didn't accept Christ.

It could be literal, or it could be John's attempt to explain something he didn't understand or couldn't put into words.

That said, most Christians don't realize that there is a difference between where you go when you die and the Lake of Fire mentioned by John.