As pointed out in the introduction to Luke 6:17–49, now, at the end of the sermon, there is a warning to take the teaching of Jesus absolutely seriously. Jesus says here, you are not truly serious if you confess him as Lord with your mouth but your actions deviate from his instructions.

That this also applies to disciples of Jesus today is made clear in Matthew 28:20. For after his resurrection, Jesus is with the eleven apostles in the same place where he gives this teaching and in Matthew 28:20 he says that they in turn are to instruct new disciples to abide by all that he himself has instructed the eleven. These instructions cover more than is in this talk, but it certainly includes this teaching about the attitude and behaviour of the citizens of God’s kingdom.

Two points of explanation are significant in this verse. Firstly, the claim Lord, Lord is more than a mere form of courtesy; it also shows that he is rightly addressed as the One who speaks with divine authority—see also how Matthew concludes the Sermon on the Mount in Matthew 7:29. Secondly, Jesus says something like, You do not do all the things I tell you to do. This is not discounted in the translations, what I tell you. But the word what in Greek here is plural. A citizen of the kingdom is characterized by doing all that his Lord tells him (cf. James 2:10).