It is a fact that OP's description of events does not give us an example of a Christian being fake, so right of the bat, I'm not sure why anyone is accepting his premise. I'm not shaming OP for being stupid; I'm pointing out that his resentment of his cousin is misplaced.
You have made a couple of vague pronouncements about what Christians are like: namely, that many Christians are Christians for show, and that Christians are the most vocal in their judgment of others. You haven't done anything to back up what you are saying, and I'm not sure why anyone should accept your positions on these issue. Cite a study.
Other than that, you've gotten into a discussion with Jack Handy about sociopath's ability to feel guilt, which has nothing to do with Christians being fake. So out of the two of us, I would argue I'm staying more on topic.