I haven't read more than a few pages of the LaHaye/Jenkins series (just shelved many, many copies at a public library). And it is probably my literary (as opposed to theological) bias, but I don't find the popularity of this series quite as alarming as many commentators, particularly in Britain, seem to. It looks to me like a parallel to the phenomenal success of other "Christian/inspirational" genre publishing, such as romances.
Genres like thrillers and romances are enormously popular as entertainment, but there is a large market of folks who are uncomfortable with certain conventions, like the context of sex in a traditional romance. So they buy these other series. I think readers buy these apocalyptic books because they want to read thrillers, but regular thrillers make them uncomfortable, so they substitute Satan and God for the bad/good guys in, say, Tom Clancy.
Certainly, if large numbers of individuals actually want to provoke Armageddon in the Middle East then that is alarming, but even most of those "true believers" are not active participants in the destruction. After all, like non-Zionist Jews before 1948, they hold that this is all in the hands of G-d and we have nothing to say about it at all.
I don't think that most readers are buying fiction because they want to enact it in their actual lives. They buy it because they are bored.
Reading: Paradise Lost by John Milton
Reading Like a Writer by Francine Prose