I see it manifested in the christianity group quite often, in short posts that usually say something along the lines of "Ain't Jesus great? I love Jesus!"
There's certainly nothing "wrong" with declarations like this, apart from the fact that I personally find them mildly annoying. So, of course, I overanalyze to figure out why.
I see several possible reasons for posts like this. But as a preliminary observation, I don't think the motivation is to generate discussion within the community (unless the poster is simply after a bunch of "Amen!" and "You're darn tootin'!" replies). I guess I'm goal-oriented in that respect ... personal thoughts and reflections, to me, more correctly fit within one's personal journal; whereas coms are for topics of discussion. So I guess the first thing to recognize is that not all of the "yay God" posters share this paradigm.
But assuming the purpose IS to generate discussion, then to what end? Matters of faith for me don't rely on community support. Do they for others? Rather, if I deeply feel something is right or wrong, even after thoroughly thinking it through, it's not likely that I'll be dissuaded from that by reason, even if a majority of my peers may disagree ... so are these kinds of proclamations really admissions to others of the faith that the poster needs some reassurance, in terms of the "You go!" and "Jesus rocks!" type of responses he or she seems to be soliciting?
Is it the particular flavor of the com that makes declarations like this more welcome, or expected, than in other topical coms? For example, I hardly ever see anyone in the damnportlanders com sporadically post that "PORTLAND RULES!" Likewise, no one in the metaquotes com excitedly writes, apropos of nothing, "Metaquoting other peoples' LJ comments is so cool!" In these cases, it's more or less an unstated assumption; without which you probably wouldn't be posting to the com in the first place.
I guess in more general coms like philosophy, an enthusiastic holla for Hegel or Kant might not seem out of place, but in christianity, there's pretty much only one dude to cheer for. Or three, I guess, depending on how you see it.
EDIT: ok, you goofballs. DP post 1 ... DP post 2 ... DP post 3 ... DP post 4 ... and bonus DP_snark post!
EDIT 2: DP post 5 ... muahahaha!