Very few sermons close off as forcibly as the Sermon on the Mount. Jesus summons people to follow him, and the way he does this is to clarify the sort of followers he has in mind (beatitudes), the salt and light vocation, the surpassing righteousness he expects, and the simplicity of doing things with integrity and trusting God for provisions, and then a series of comments about discernment — and then Jesus simply calls people to follow.
Jesus is here not trying to frighten folks; he’s warning the arrogant possessors of gifts who think they’ve got a claim on God because of their service, their success, and their supernatural works. Jesus summons those who hear his words to follow him.

And for Jesus following him cannot ever be reduced to what one says. One can say “Lord, Lord” to Jesus but calling Jesus “Lord” is nothing if it does not mean following Jesus. And here is perhaps the shocker — following Jesus also does not mean ministry experience or giftedness. For Jesus is setting his teeth against those who (1) call Jesus “Lord,” (2) exercise gifts of significance, but who (3) can be called “doers of lawlessness.”
Giftedness does not equal redemption.
Allison suggests that what counts with Jesus is not supernatural giftedness but the gifts of charity and mercy and compassion — and there is good reason to think Matthew 25:31-46 can be brought into play here because it too is a judgment scene.
Finally, a point simply cries out for attention: anyone who thinks final redemption is secure because one has “received Christ” will not find support in the Sermon on the Mount. Redemption comes to those whose lives reveal the presence of God’s redemptive grace. Someone, I think John Calvin, said that we are neither saved by works nor without works. Jesus would utter a hearty “Amen!” to that one.