What does Matthew 9:13 mean?
A recent question from the Pharisees was more of an accusation: why does Jesus eat with tax collectors and "sinners?" Why would a supposedly-righteous man be seen in the company of immoral people (Matthew 9:10–11). The Pharisees themselves would never share a meal with people who openly break God's law. Nor would they lower themselves to be seen with anyone who didn't follow their own rules of conduct.Jesus has quipped that healthy people don't need a doctor, but sick people do. His point is twofold: that to properly love and care for others, we need to minister to those who are caught in sin (Matthew 5:44; 2 Corinthians 4:3), and that arguing otherwise is as ridiculous as a doctor who refuses to go near sick people.
Now Christ tells His critics to examine Hosea 6:6, where God says "I desire mercy, and not sacrifice." As He typically did, Jesus quotes the Greek translation of the Old Testament, known as the Septuagint. The original Hebrew of this verse uses the term he'sed, an important expression of faithful, deep, graciousness. The ESV, for instance, translates the term in Hosea 6:6 as "steadfast love." The Pharisees were not in the mercy business. Their strategy for motivating the people of Israel to live right before God was to set the standard very high and then live up to it themselves. From that position, they looked down in judgment on those who could not or would not join them in their pious lifestyles (Matthew 23:2–7). Jesus' willingness to spend time with tax collectors and harlots and other disreputable people as if those people were "okay" was maddening to them.
Jesus tells the Pharisees that He did not come to call the righteous. He came to call sinners. The Pharisees assumed themselves to be righteous already. They did not think they needed saving. Jesus came to call those who understood themselves to be sinful and in need of mercy, forgiveness, a Savior (Matthew 7:6). When given a glimpse of the loving face of God in Jesus, seeking people flocked to Him (2 Corinthians 4:6). They still do.