As a conclusion to the parable of the two sons, Jesus declares: “tax collectors and prostitutes” are entering the kingdom of God before you! (Matthew 21:31b-32). They are entering the kingdom before the Jewish leaders who questioned Jesus’s authority because the teachers refused to believe John the Baptist and Jesus.
Jesus says the bottom level of purity in the Jewish tradition will enter the Kingdom before the top levels. There is something more important than external purity issues that qualifies one for entrance into the kingdom: Repentance from sin, a “pure heart” that can only be created by God, and the kind of honest acknowledgment of one’s need (as in the case of the tax collector and the Pharisee parable in Luke 18).
This is a continuation of the “first shall be last” theme that Jesus began teaching in Matthew 19-20. Those that expect to be a part in the Messiah’s program are not, and those that probably do not expect to enter the kingdom are included because of their humble faith.
That the tax collectors and prostitutes enter the kingdom at any time would shock his Jewish audience. But to enter before those who are ritually pure, students of the Law is an affront! For some commentators, the religious Jews have no chance at getting into the kingdom because of their current unbelief. But this is not how the verb is used throughout the rest of the New Testament, so likely what is meant here is that the Pharisee may yet enter the kingdom, but he will be at the “end of the line!”
Note the tense of the verb: tax collectors and prostitutes are entering the kingdom, a present tense verb. Not “will enter” but are currently participating in the kingdom. This is because Jesus is the king, and because he is present the Kingdom is present. Tax collectors are celebrating with Jesus and the Religious Leaders are not. Jesus is a friend of sinners, the Religious Leaders are not.
The reason these chief priests and elders will not enter the kingdom of God first is that they did not believe John as the prostitutes and tax collectors did. John taught the “way of righteousness” which seems to mean that he was teaching the people what the will of God was.
In Matthew 3:15 Jesus says that he must be baptized to “fulfill all righteousness,” implying that it is God’s will for him to be baptized even though he does not need to be cleansed of sin. John the Baptist pointed the way to the Messiah, not the Messiah himself. Those that looked to what he showed are the ones that are now participating in the kingdom.
The phrase “way of righteousness” is an Old Testament and intertestamental phrase, found in Proverbs 8:20, 12:28, 16:31, 2 Peter 1:21, and the intertestamental sources. John came as a teacher of righteousness, but never claimed to be the source of that righteousness, he simply pointed the way to the righteousness of God, the Messiah Jesus. This is all very similar to Luke 7:29-30, there Luke makes it clear that the low levels of Jewish society believed John, but the teachers of the Law did not.
Jesus forces the teachers of the Law to make the decision which son did the will of the father, then transferred the guilt of the first son to them. The teachers of the Law are the ones that should have understood John, and later Jesus and immediately followed them. They are the ones that said they would do the work (expecting the Messiah), but when Jesus came, they didn’t do the work.
Because they do not do the will of the father, they are to come under judgement. This is not explicit in this parable, but in the next parable the Jewish leadership is to come under judgment.