‘What will the Lord of vineyard do?’ The appeal is to natural justice. The Lord asks the question, because he wants his hearers to give the answer.
The conscience cannot be completely eliminated. Men will be their own judges on the Day of Judgment. They will have to acknowledge that God’s punishment of them is fair and just. They will be forced to admit all the aggravating circumstances of their sin. On the day of Pentecost, under the preaching of Peter, they understood the enormity of what they had done. Their former self-righteous resistance could no longer keep the full extent of their wickedness at bay.
You hear of a plane going down and a service is held by a nominal clergyman, and all the people are said to be in heaven. But we don’t know. Only God knows. It is confusion. Even their relatives know that in many cases, they had no time for God in their lives. But the clergyman wants to give some comfort to let people think they all are in heaven. The parable exposes us in all our many forms of unbelief.