IMO, 'politeness' stems from a self-imposed respect for another person based on a psychological empathy with the feelings or experiences of the other person. For the Christian, it logically follows from the understanding that all human individuals are created in 'the image of GOD', thus they have great value and dignity. 'Political correctness', IMO is an attitude that is unquestioningly 'caught' or assumed by the individual and imposed on everybody by the 'group mind' or opinion, e.g.-'peer pressure'. I've felt this same pressure from cultic groups that I've been exposed to in the past. It's like, "Yeah, I gotta' act this way, cause that's just the way it's done and everybody does it that way, and if I don't, then I must be wrong and I don't want to be wrong and feel icky and I don't really understand this but it must be right, cause everybody else is doing it, and 'so and so' does it, and you know he's like, uh, well you know what he's like and....."
This culture is going to 'politically correct' itself right into 'sharia law' or some other tyranny, because it has lost any 'real' basis for personal responsiblility.