Mt 21:31 ... Jesus said to them, "Assuredly, I say to you that tax collectors and harlots enter the kingdom of God before you.
The Lord Jesus was addressing the religious people in Israel here in this verse, namely the chief priests and the elders of Israel. This is a shocking statement that He made. Scandalous! The blood pressure of the religious men who heard this must have shot up.
The tax collectors were considered traitors to the nation of Israel and they were generally corrupt. The harlots were considered the low lives in Israel.
But the one thing that was going for them was that they did not have a false conscience to make them believe that they were okay with God. Moreover, they did not have any false piety to make them trust in themselves that they were righteous. They were obvious sinners to others and most importantly to themselves that they felt a desperate need to repent and come to the Savior. And so, coming to the Savior, in repentance and faith, they enter the kingdom of God.
The highly religious men in this instance, however, were the opposite. They did not find anything wrong with themselves, they became satisfied with themselves and they saw no need for the Savior.
And so, they did not repent when they should have repented and they did not come to the Savior in faith when they should have for their salvation. Hence, they failed to enter the kingdom of God.
Don't let this happen to you, my friend. Realize that you are a sinner. Realize that you cannot save yourself. Realize that you need to come to the Lord Jesus in repentance and faith for salvation.