Why Are Christians Good?

According to an atheist who names him/herself bodysaffa, replying to this post by Theist, Christians are good "because 'Jesus said'".

Huh? While that answer is certainly a legitimate answer, it is by no means the only one, no is it an answer that most adult theologically-literate Christians would give were they asked the question. Instead, they might say something like, "because being 'good' fulfills our nature as human beings, and hence results in true happiness."