According to Dennis Prager, the belief that people are basically good creates an overwhelming obstacle to creating a "good" world. In a world that believes that people are naturally good, "goodness" is taken for granted and is not taught.
There is a difference between being good in your basic nature and knowing how to be good in the outside world. Babies can hardly be said to be "bad" or "evil", and yet their total self interest and lack of regard for others - not to mention their negative effects on their local environment - can also hardly be said to make them "good" participants in society. And yet, the evidence of the innate goodness of humans is considered to be most obvious in the innocence of small children.
Everyone is the hero of his own movie. While history has come to interpret their actions in a different light, it is reasonable to assume that most of the Catholic inquisitors torturing heretics in Old Spain, and Puritans burning witches in Salem, saw their actions as good and righteous within their personal world view. It is their perception and method of being good that we now find unacceptable, not their inner nature and intentions.
Being good is a behavior pattern that must be learned by good people. One of the major causes of problems with young people today is that their parents assumed they were "naturally good" and failed to teach them how to be good.