This is a really interesting thread. I'm a newbie at vaping and I'm already thinking about where I will and where I won't. Last night I was stealth-vaping in a (large, dark) bar. I was going to go open, talk to the bar staff and ask permission, but it was Friday night-busy.
So, in church? Don't think I would. Unless I got a terrible nicotine-craving, bad enough to make me have to. But then I've been through church services without a cigarette, so I don't see that happening.
Why not in church? I'm determined to vape just about everywhere else, with respect to people around me, and a diplomatic approach to help people accept it.
I think it's to do with attention. Church is full of people trying to focus on the service. I'd have the same attitude at a classical music concert. If I saw someone else (e.g. the OP) discreetly taking a hit from a PV, in either of those places, I wouldn't mind at all. I just wouldn't do it myself. An ex used to drive me nuts by constantly taking calls on her mobile while we talked - so good conversation just couldn't happen. Just my view of it, but if I'm in church it's the same thing: I'm there to pay attention to what's going on, otherwise I don't want to be there at all!
Actually, church is different from a concert. I'm a classical musician myself. I'd love to see a member of the audience vaping while I'm on the stand playing. To me that shows they're there to enjoy themselves and are enjoying themselves. But that's a whole different story about conventions in music concerts. Church, to me, is different, even though I'm not a conventional believer.