If a Christian is one who follows Christ, then Christ will decide whether or not they are truly following him. Most, I'm afraid, are likely not following him, despite calling themselves "Christian." I have had only a handful of minutes this entire lifetime wherein I was truly following Christ. Yet, I'm learning from my mistakes.
The problem is self-concern. Any self-concern turns you away from Christ and God (Love). If you love others as yourself and wish for them everything they desire, even to your own detriment, then you are following Christ. You are turning the other cheek, effortlessly, and without any concern for the self.
If you are following Christ, then you are not arguing with others about these things. Arguing is full of self-concern. Giving these things to others is the way. If they are not interested, then leave them and give these things to someone who is interested. That is love.