Who deserves the kingdom? Who do you want in the kingdom? We need to be constantly reminded of who our King is and how and with whom he builds his kingdom.
So here is the call of Christ to Levi, found in his sin: "Follow me."
Here, too, is the compliance of Levi: he left all, rose up and followed him, showing a disciple's response.
Then we see a crowd of sinners - Levi's colleagues and cronies - eating and drinking with the Lord Jesus as the guest of honour.
Further, we see the complaint of the scribes and Pharisees: as far as they are concerned, this is by no means what the kingdom of God ought to look like.
Finally, we return to the call of Christ. He reminds the Pharisees that it is not the righteous, but sinners, that he has come to call.