"But go and learn what this means: 'I desire mercy, not sacrifice.' For I have not come to call the righteous, but sinners." ~Matthew 9:13
In this statement, Jesus is emphasizing that He has called sinners to repentance, not people who are righteous in their own eyes. This is critical in understanding salvation, because we cannot attain righteousness by our own works. Only by grace through faith are we saved. By repenting of our sins and placing our faith in Jesus Christ, His righteousness is imputed to us, which gives us a righteous standing in front of God.