Cannot comprehend

I seriously don't understand why some ppl can call themselves christians because they can't even show the smallest amount of filial piety. It's probably because I've been brought up by a "Confucius-thinking" family and thus the importance I place on filial piety. If the parents are really jerks, I'd understand. But they are truly caring parents who work hard to raise their children; who try their best to provide as much as they can for their children. Plus, these children do not have mental disabilities, which could cause one to act like a horrible person. Children are obliged to treat their parents well and try not to disobey them, just like how they are obliged to take good care of them. The fact that these children are christians and are supposed to be learning about morals just makes me mad when I see them do stupid and mean things to their parents. What makes them do this, can someone enlighten me?

*I'm not saying that ppl who aren't christians don't obey their parents. I am merely pointing out that when one is constantly being reminded of the importance of morals, and claims to be a "true christian", he should be living up to what he preaches by and what he calls himself to be (or at least be trying to).