How does the owner respond? In the parable it is as if he tries to come up with an explanation which accounts for this extraordinary behaviour. He seems unwilling to believe the worst about these tenants.
From time-to-time God sends a messenger to speak with us. How many times has God spoken to you and you have pushed him away? We owe God our lives. Perhaps you can remember times in your life when the gospel came to you. You know how you responded. You refused to take the message seriously. You scorned the messenger and tried to make them feel uncomfortable in attempting to reach you. You certainly did nothing to encourage them to say more. Maybe you responded better than that. The gospel made sense to you; you saw its consistency and power. But when you became aware of the cost of discipleship, you turned away, though you knew that you risked God never speaking to you again.
In representing God by this vineyard owner, and in picturing him as acting as if he could still get the tenants to do the right thing, Christ is not for a moment suggesting that God has an unrealistic view of what is in the human heart. He knows exactly what we are (John 2:24-25). The parable portrays God in this way not to make him naïve about human behaviour, but to express the amazing lengths his grace and patience is prepared to go. By comparing God to someone who makes unreasonable efforts to win over recalcitrant tenants, the parable deliberately ignores the omniscience of God and focuses on just one aspect of his character – his amazing longsuffering.