Rick,
As you said you were interested in the question kind of generally,
here's a study that you might find helpful. The bottom line is that it suggests (and gives what strikes me as a plausible explanation of why) that religious people are
more likely to fear death than non-religious.
Now, with that said--and the article does a good job of pointing out some of this--the question itself ("Do you fear death?") isn't very precisely worded. What most people fear isn't really
death as much as it is either the pain or suffering associated with it or maybe more abstractly the end of their ability to enjoy the pleasures of life, having to leave others they love, etc. But as people get older, as they are in chronic pain, as their friends and family have died off, etc., then death doesn't have a lot to threaten them with anymore, and so all of that becomes less threatening! Still, you put a gun in anyone's face and threaten to pull the trigger and they're going to get scared. That's just what fear is. It is the brain's response to a threat. It's a biological response. But asking about some existential fear? I don't know that you are going to get very far. I've also read studies, by the way, that demonstrate I think rather well that such matters are highly influenced by what I might call your "death horizon." For instance, it's well known that older people tend to value relationships and quality time more than younger people, as they tend to value professional development and finding a sense of purpose in some activity. (And that's not to say, btw, that either group has a monopoly on either view . . . we're just talking about aggregate tendencies.) There have been lots of hypotheses to explain that, but one I found especially compelling (and supported by some studies) is that in moments of heightened awareness of one's own mortality, one's values become more personal and relational and less professional and activity-oriented. And the inverse also tends to be true. The less one is immediately aware of their own mortality, the more one's values are professional and activity-oriented and the less they become personal and relational. I, then, can think of several reasons why religious folk might have something like a smaller "death horizon" than a non-religious person. But, again, no subgroup of any kind has a monopoly on any of this.
Anyway, just some thoughts for you to consider, and if it matters to you at all, all of this is very much in line with what I've witnessed for the past four years in hospitals and nursing homes. I've literally sat at the bedsides of probably 10,000 people or more. I've spent over 5,000 hours in that kind of work and been with well over a hundred people as they died (and so certainly hundreds of family members as their loved ones left this world). My point is just that my anecdotal evidence lines up with what I've seen in the studies, so take that for whatever it is worth!