What was it in the words and person of Jesus that - in particular - the tax collectors and sinners were so eager to listen to Him? What was it in the hearts of the Pharisees and the teachers of the law that they found this so annoying?
Jesus explains this very clearly in the parable He tells in response to precisely this. Jesus here compares Himself to a shepherd who is herding a hundred sheep but - suddenly - misses one. Then he leaves the ninety-nine in the open country and goes after the lost sheep until he finds it. And when he finds it, he celebrates with his friends.
The Pharisees and the teachers of the law despised the tax collectors and sinners. This was no wonder, for they were very content with everything they had achieved in religion.
Today it is still the same. Everybody who has been able - although with great effort - to build a Christian life thanks to his strength of character and will-power, has every reason - looking upon himself - to despise people who keep failing. But Jesus rebukes those conceited people, for because of their self-righteousness they have never submitted to the righteousness of God, and they have never learned to live by grace, though they can talk quite piously about it.
When the Bible says that Jesus has come to seek and save the lost, the word ‘lost’ does not only refer to social outcasts. It means also those people, who - however successful they think they are in this world - are lost in God’s eye, because they did not seek God’s righteousness.