People naturally resist moral change.  Each time a person becomes aware of, hears or reads the Word and fails to respond to God in repentance and correction [change, growing in grace and knowledge of the Lord Jesus Christ], a crust forms over his heart.  He becomes less sensitive to moral truth (less able to hear and respond to God) and better able to rationalize away his sin.  This is characteristic of all people.

”Son of man, go to the house of Israel and speak with My words to them.  For you are not sent to a people of unfamiliar speech and of hard language, whose words you cannot understand.  Surely, had I sent you to them, they would have listened to you.  But the house of Israel will not listen to you, because they will not listen to Me; for all the house of Israel are impudent and hard hearted.”  (Ezek.3:4-7)

To reach such a person and break the crust [convict], it is necessary to penetrate the defenses he is unknowingly [blindly] employing to maintain status quo.  Direct confrontation of sin at this point often has the effect of raising all the rationalizations [justifying self and placing the blame elsewhere] in defense of the status quo.

Telling stories is one of the best ways to slip past such defense mechanisms without triggering them.  Direct teaching raises all those defenses (self-justification, blame someone or circumstances, etc.) unconsciously, but stories connect with one's sense of right and wrong.  They can be used to rouse the ire [indignation] of listeners to respond with judgment without realizing they have nailed [ensnared] themselves.  Nathan the prophet’s approach in confronting king David with his sins of adultery and murder (2 Sam.12), is the classic example.  Nathan used subtlety with the king who was judge and acted in God’s behalf.  Jesus does the same thing.  In the parable of the great banquet (Lk.14:15-24), the listeners are astonished at the bold rudeness of the excuses the invited guests make.  In so doing, they judge themselves as unworthy of the kingdom.

Besides entrapment, there is another effect that the parables of the wicked tenants (Mt.21:33-43) and of the great supper bring out - justification (vindication) of the host's action.  In the parable of the great banquet, the insulting and dishonest excuses of the invited guests justifies the host’s anger and frees him to offer his gracious hospitality to whomever he wishes.

In Matthew, events and teachings are connected and flow in a way that builds as the narrative unfolds.  Jesus begins discussing God’s sovereignty prophetically in the parable of the workers in the vineyard (Mt.20:1-16), where the reasoning that the owner may be gracious, if he wishes, is unbreakable.  His next parable, the two sons (Mt.21:28-32), continues the flow of thought driven by events beginning with Jesus’ proclamation that the kingdom of heaven consists of people who come to Him as little children (Mt.19:13-15).  The parable of the two sons directly indicts the Jewish leaders for not believing John the baptizer.

In the parable of the wicked tenants, Jesus asks the chief priests and elders of the Jewish people, “What will the owner of the vineyard do to those wicked vinedressers when he comes (v.40)?”  The actions of the husbandmen are inexcusable and their guilt is apparent.  The question comes in the flow of events leading to the moment.  These leaders have not approached Jesus in a forthright manner or with honest questions.  Their intentions were to discredit Jesus.  They were not seeing what He was doing or hearing what He was saying.

The force of what Jesus is asking is “What will the owner be justified in doing?”  “What do these husbandmen deserve?”  “What does the owner have every right to do to these men?”   The force of what Jesus is saying is being carried by the flow of occurrences in the passage.  Jesus has brought them to the place where they themselves justify God’s moral judgment upon them.  They understood the question, and answered, “He will destroy them and rightly so, for they deserve nothing less.  [This translation captures the essence of what they meant.]  “And lease his vineyard to other vinedressers who will render to him the fruits in their season” (v.41).  Once again God’s sovereignty is acknowledged, this time by the Jewish leaders.

In the parable of the wedding feast (Mt.22:1-14), the invited guests are inexcusably guilty, the host’s justification for punishing them is clear, and his right to invite whoever he wishes [sovereignty] is unquestioned.  The climax comes in the exclusion and punishment of someone confronted with the question of how they gained entrance to the celebration “without a wedding garment” (v.12).  The point is that one comes to fellowship with God at the gracious invitation of God and by the sovereign choice and work of God (clothed in the righteousness of Christ), “for many are called, but few are chosen” (v.14).

Parables intended to point out blind spots [cataracts, calluses on the heart] and bring people face to face with their sin must engage the person in a third-person moral event whereby he unknowingly elicits judgment upon himself.  Catching people up in such stories involves deliberately creating and presenting them.  Creating such stories necessitates identifying the sin, sinful attitude, or wicked motive to build the tale around.  And, no parable is sufficient alone.  It is a device serving to engage people in the moral judgment of a third party situation.  Direct confrontation follows to apply the person’s own judgment to his situation and press him in the hope that the condemnation will force his realization of sin resulting in repentance.  Nathan did this with David (who repented) and Jesus did this with the Jewish leaders (who repented not).