I think religion has always been very important to him, he wanted to be a Franciscan (i.e. Catholic) priest when he was younger, but decided against it after a year. Obviously he's into Scientology now.
He's probably not afraid of trying new or unusual things (like Scientology) (although Scientology probably limits drug-taking and so on). I suspect that even if he wanted to leave Scientology, he probably couldn't, at least not openly, they probably have too much on him.
He's very personable and friendly, aside from his interest in Scientology, which I guess is basically a subject his peers on acting projects know not to bring up.
Impressionable? Maybe, but religious belief is common (as is belief in supernatural phenomena, or other beliefs with no evidence like Socionics), so I have to be careful about not singling him out on that point.