Nothing wrong with CCing in church. There was a time when it was not necessary because churches were considered "off limits" by friends and foes a like when it came to criminal acts and such. That time may come again, but now is not that time. Better to air on the side of caution.
I am %100 against OCing in church unless your church is used to and supports that sort of thing. I'm against it for the same reason I'm against ******** from both parties (however in my experience, the local republican groups are more guilty of this than the other) trying to include their little political events and agenda in the church announcements and even during the service.
People come to church to focus on and pay homage to their creator for just one hour out of their week. Anything apart from that has no buisness inside a church service. There are times and places for standing up for the 2nd amendment.........church is not one of them. CCing accomplishes the defense aspect but allows for people to focus on what really matters at church. Now before someone talks about the need to prevent a crime even at church......no guy that is intent on blowing away a church full of people is going to be stopped by seeing your gun (if even does see it). A liquor store or gas station is an entirely different story with a different motive. So, to my mind, it makes more sense in....this particular scenario at church... to CC anyway as crime at church is unlikely to be prevented except by shooting said psycho (which CC takes care of).
But if it's common in your church (would be curious to see that congregation) , I suppose it doesn't matter as it won't be as distracting.