People say that all the time: “I’m basically a good person.” What I think they mean is that they are basically moral. They don’t lie or steal or cheat or murder. But, when you read the Sermon on the Mount, you see how inadequate that idea of goodness is. For Jesus, goodness is not primarily moral, but spiritual–it’s about being like God, who is even kind toward those who are evil: “For he makes his sun rise on the evil and on the good, and sends rain on the just and on the unjust” (Matthew 5:45).
It is possible to be perfectly moral and at the same time remain selfish, contemptuous, and resentful. In the Sermon on the Mount, Jesus is explaining that true goodness is active love toward others–it’s not refraining from doing evil–it’s actively doing good, even towards those who are doing evil.
I’ve read the Sermon on the Mount many times, but each time I read it I am reminded that there is nothing else like it in all of human history.