As a missionary my comp. and I went into a BA meeting to sit through it (can't remember why now..)but the preacher / teacher saw us come in and sit at the back and then I sat in awe while he changed his whole talk to attack us - it was incredible. I had to give him kudos for being so quick on his feet but the gist of what he said was -
All you need is grace, the gospel is not works or performance of tasks its is purely belief anf faith, the gospel is contained in the new testament and doesn't need any additional scriptures, true christians don't wear badges and travel half way round the world to knock on doors.
Serves us right for being cheeky enough to walk in on his meeting!
Another time we met a pastor who invited us over for 'bible study' so like grinning idiots we said yep - we turned up to find we'd been set up, several hard core brothers with anti-mormon literature ready to rumble.
My experience of christian religions is that they all have a fairly similar outlook (and their own phrases to describe and label people) - at the core of christianity is the idea of being saved so there is no mileage from the pulpit in saying that non-christian churches can get you to heaven. All christian churches have their unsaved, heathen, goats, gentile, unbeliever labels and then there is the investigator, student, padowan and once they actually join they become saints, publishers, anointed, chosen, Israel, disciples, believers and finally when they fall off the other end of the conveyor belt backsliders, apostates, less-actives, inactives, weak, Sith etc... I think that most christian religions are fundamentally the same but it is the application of principles that causes the problems - shunning is an example of a principle out of place (IMHO) but there are plenty of extreme examples throughout christianity and all backed up by scripture.