I don't know what D & D clerics are like, since I'm unfamiliar with the game.
One thing is certain, though: these guys and gals definitely treat being priests and bishops as a role-playing/dress-up game.
They certainly don't act as though Christianity is a matter of life-and-death... which it is.
I've never actually played it, so I'm not terribly familiar with it. Something about the guy in the greenish vestment tells me he would enjoy waving his staff around and yelling "I cast Dispel Evil!"
Since my last reply I remembered that the Archbishop of Canterbury is or was an "honorary Druid", which is exactly the sort of thing you were talking about. Some dress up and play at being pagans so they can hold ye olde quaint ritual, others dress up and play at being Christians so they can hold ye olde quaint liturgy. And neither can reasonably see any conflict, because they don't really mean any of it.