“But what do you think? A man had two sons. He went to the first and said, ‘My son, go, work in the vineyard today.’
“He answered, ‘I don’t want to!’ Yet later he changed his mind and went. Then the man went to the other and said the same thing.
“‘I will, sir,’ he answered. But he didn’t go.
“Which of the two did his father’s will?”
“The first,” they said.
Jesus said to them, “I assure you: Tax collectors and prostitutes are entering the kingdom of God before you!
(Matthew 21:28-31 – from Holman Christian Standard Bible® © 2005 by Holman Bible Publishers)
The parable Jesus told was about obedience. His instruction to the chief priests and elders in verse 31 was based on their correct answer to His question in verse 31: “Which son did His father’s will?”
He informed them that it was by their obedience to God that prostitutes and treasonists were entering the Kingdom of Heaven. He was not talking about going to Heaven when they died. That access had not been purchased with His blood yet, and when that did happen, was the only access.
As He informed some people who called the Holy Spirit “Beelzebub” in Luke 11, the Kingdom had already come to them (vs. 20). Entering it was possible through hearts that were surrendered to the will of God.