Jesus warned his followers to be on the lookout for wolves in sheep’s clothing (Matthew 7:15-20). In 7:21-23 Jesus takes this warning a step further: not everyone who calls Jesus “Lord, Lord” will enter into the kingdom of heaven. For example, In Matthew 25:11 the five foolish women who were not prepared to wait a long time for the bridegroom call out to the groom “Lord, Lord” when they want to enter the wedding feast.
The warning is clear. People are not “right with God” and true disciples of Jesus by acknowledging that God exists or that Jesus was a good teacher or even by trying to live the words of the Sermon on the Mount (those “Red Letters”). Some people will claim to follow Jesus and do miracles in his name, ye ton the great day of God’s wrath, they will be outside the Kingdom because they were never really followers of Jesus.
“On that day” refers to a judgment prior to entering the kingdom of heaven. John Nolland suggested the phrase “on that day’ (ἐν ἐκείνῃ τῇ ἡμέρᾳ) can be a fixed eschatological expression.” The Body of Christ is judged at the judgment seat of Christ prior to this general judgment, we do not need to worry about being sent away when the kingdom comes. However, the warning is still important, at the rapture many who were thought to be Christians will not be raised to new life.
These false disciples claim to have prophesied, done miracles and cast out demons in the name of Jesus. If they were not true followers of Jesus, how did they do miracles in the name of Jesus? Lying signs and wonders are common in descriptions of the last days prior to the return of Jesus.
Jesus reverses the expectations of these reputed followers of Jesus: “I never knew you” (v. 23). Although they thought they were doing the very things that merited their inclusion in the kingdom, their deeds were actually fruitless.
This conclusion to the Sermon on the Mount is similar to the conclusion of the Olivet Discourse, the other “sermon on a mount” in Matthew’s Gospel. In Matthew 25:31-46 many will stand before the throne of the Son of Man and find out they will not enter the kingdom of heaven, but will go to “eternal punishment” (25:46), where there is darkness, weeping and gnashing of teeth (25:30). The Son of Man also says to the goats “depart from me” in Matthew 25:41. In this case the dismissal is to eternal fire prepared for the devil and his angels. A similar phrase appears in Psalm 6:8 (LXX 6:9): “Depart from me, all you workers of evil” (ἀπόστητε ἀπʼ ἐμοῦ, πάντες οἱ ἐργαζόμενοι τὴν ἀνομίαν, LXX Ps 6:9).
The shocking moment for these false disciples is Jesus calling them “evil doers.” This is another phrase which turns up in the conclusion of a speech in Matthew. At the end of the Parables of the Kingdom the day of the Lord begins with God sending his angels to gather up all the causes of sin and law-breakers (τοὺς ποιοῦντας τὴν ἀνομίαν, 13:41), a similar phrase as Matthew 7:23 (οἱ ἐργαζόμενοι τὴν ἀνομίαν).
It is unlikely these false disciples were sinning as pagans, like a modern televangelist who preaches against the very sins he is committing. But their failure to uphold the whole law is shown in their treatment of the poor and needy.
The follower of Jesus must make a faith commitment, believing Jesus’s death on the cross pays for their sin and his resurrection gives them new life (2 Cor 5:17). This new life ought to natural grow and develop over time, there ought to be a maturing process similar to a child growing and developing normally. Jesus’s call to his disciples at the end of the Sermon is to “be what they are,” growing and developing fruit in their personal lives and living out their faith through concrete actions directed at people who are in genuine need.