Do not think that I came to invalidate the Law or the Prophets; I came not to invalidate but to fulfil. 18 For truly, I say to you, until heaven and earth pass away, one iota or one dot may not pass away from the law, until all things should take place.
Jesus explicitly attaches a temporal limit to the validity of the Torah: ‘until all things take place (panta genētai)’. The allusion to the new heaven and earth imagery of Isaiah 65:17; 66:22 points to an eschatological-historical crisis of judgment and restoration that is imagined as a renewal of creation. We may quite naturally connect ‘until all things take place’ with Jesus’ assurance in Matthew 24:34 that the present generation of Jews would not pass away before ‘all these things take place (panta tauta genētai). ‘All these things’ are the desolation of Jerusalem and the vindication of the Son of man. This is Jesus’ eschatological horizon, and we should allow it to frame his teaching.
In what sense does Jesus ‘fulfil’ the law? Precisely in bringing a sword of judgment rather than peace (Matt. 10:34): this is how he ‘fulfils’ the law (cf. Deut. 28:25) and the prophets (cf. Ezek. 21:2-3). So the law now condemns Israel to destruction. It remains in force, therefore, until that point, until the flood of God’s judgment comes and sweeps the house away, when it is the house built on Jesus’ word that will remain standing.
When he says in 5:20 that their righteousness must exceed that of the scribes and Pharisees if they are to enter the kingdom of heaven, he is making a more or less rhetorical point: Israel faces the judgment that the law prescribes because the leaders of the people have not been righteous.