Later, Levi invited Jesus and his disciples to his home as dinner guests, along with many tax collectors and other disreputable sinners. (There were many people of this kind among Jesus’ followers.) But when the teachers of religious law who were Pharisees saw him eating with tax collectors and other sinners, they asked his disciples, “Why does he eat with such scum? ”
When Jesus heard this, he told them, “Healthy people don’t need a doctor—sick people do. I have come to call not those who think they are righteous, but those who know they are sinners.” (Mark 2:15-17 NLT)
There are two types of sick people. There are those who are obviously sick. They know it and everyone around them knows it because of their outward symptoms. And there are those that do not know they're sick until it is revealed to them -- stories like people who feel well but go to the doctor for a basic check up and the doctor discovers a medical condition that was not obvious to the eye.
In the same way, there are some that know they are sinners. It is obvious based on their actions (murderers, robbers, etc...). And there are some that don't really see themselves as a 'sinner'. Instead, they would see themselves as a pretty good person. These folks need to be told they are 'sick'. They, too, are sinners, they just don't see it.
The Bible tells us that we are ALL sinners. No one is righteous. No, not one. We ALL are in need of mercy. We ALL are in need of a Savior, a Doctor.
Which type of 'sick' person are you? He comes to forgive, but first we must see how desperately we are in need of forgiveness. Even a 'good' person needs Jesus.