In the first century, when a person was blind or otherwise impaired, it was often interpreted as a sign that that person or the parents of the impaired individual had done something wrong. Blindness was a punishment. So was leprosy, infertility, headaches, mobility issues, dementia, and just about anything else that seemed undesirable. Some people still think like this. If something is "wrong" in a person's life, that person did something to deserve it. The Bible (and the religious writings of other faith traditions) even suggests that a good person receives rewards in life and a bad person receives punishments.
This causes a quandary, however, when such thinking is challenged by reality. Sometimes bad people seem to be rewarded, and sometimes good people seem to be punished. This was even a problem for people in ancient Israel. The Wisdom books of Hebrew scripture highlight the struggle. Even as it is asserted that wise, good, faithful, honorable people will be rewarded and foolish, wicked, malicious, people will suffer, there are books that point out that this isn't always so. Job and Ecclesiastes, for example, are writings that directly wrestle with the realization that reality doesn't line up with simple expectations. Good people don't always have an easy life; bad people don't always suffer. The conclusion of Job is that Yahweh is in charge and shouldn't be questioned. The conclusion of Ecclesiastes is that we should enjoy life while we have it and trust that all will be balanced out as Yahweh sees fit.
Over time, people started to think that maybe things wouldn't be judged and balanced in this life, but that people would receive their reward or punishment after this life was over. An eternity in heaven or an eternity in hell would be the ultimate consequence of life. Good people will be rewarded, and bad people will suffer.
The New Testament expresses that we can see who the good people and bad people are by their actions. As a typical example, Matthew 7:16-20: "You will know them by their fruits. Are grapes gathered from thorns, or figs from thistles? In the same way, every good tree bears good fruit, but the bad tree bears bad fruit. A good tree cannot bear bad fruit, nor can a bad tree bear good fruit. Every tree that does not bear good fruit is cut down and thrown into the fire. Thus you will know them by their fruits." Another example is 1 John, in which the author proclaims that the distinguishing characteristic of "children of light" is that they live out the commandment to love. By contrast, "children of darkness" can be clearly distinguished by their expressions of hatred.
Lots of people still believe that there are good people and bad people, and they might even agree with the idea that you can tell the difference between good people and bad people by their actions. Some people are convinced that the eternal souls of good people will go to heaven and the eternal souls of bad people will go to hell. (Incidentally, this is not the message of most Christianities, but that's another matter.) We look around us and it makes perfect sense to say, "That murderer/extortionist/ rapist/thief was just a bad apple," or to be equally impressed by what a "good person" someone is when we see them being generous or helpful. This either/or mindset makes a lot of sense to our brains, and we can often make it fit with our experience if we don't look at people too closely. And it's wrong.
There are no good people. There are no bad people. The allegory doesn't hold that "good trees" only bear "good fruit" and "bad trees" only bear "bad fruit." People make choices. People are capable of making choices that contribute to the well-being of themselves and others. People are also capable of making choices that seem to benefit themselves at the expense of others. The specific actions of people might be reasonably labeled as good or bad, but then you have to define what that means. Maybe good actions are those actions that increase well-being and bad actions are those that cause harm. Some actions would seem to be neutral. The point is that every person is capable of choosing from a whole array of potential actions.
Thus, there are no good people, and there are no bad people. There are just people. People make choices. We like some of the choices that people make. We don't like other choices. We feel badly about some choices we make, and we feel happy about other choices we make. We are people. We make choices. We are not good trees or bad trees, and the fruit of our lives is a whole array of flavors.
As we are able, may we have the confidence and courage to make choices that contribute to the genuine well-being of ourselves and the people with whom we share this planet. And when we choose otherwise, may we have the humility and perseverance to try again. You are not a good person. You are not a bad person. You are a person, and you have the capacity to choose what you will do.