Brandon Levering, looking to the Sermon on the Mount, gives an answer:
In the Sermon on the Mount Jesus is portrayed to us as a new Moses, who comes out of the wilderness and ascends the mountain (5:1-2) to give God’s instruction. Jesus came not to relax or remove the Law, but to fulfill it (5:17-20).
And yet, Jesus is more than a new Moses, for he speaks with the authority of God himself (cf. 7:28-29). He is no mere prophet shouting, “Thus says the Lord.” Rather, Jesus says, “You have heard it said before…but I say to you” (e.g. 5:21-22). Throughout the sermon Jesus speaks on direct behalf of his Father in heaven (e.g. 5:45-48; 6:1-18; 7:7-10). He speaks as the divine law-giver and judge (7:21-23). And he speaks as the one in whose words we find wisdom and life (7:24-27).
Jesus is the King who speaks as God. Which means that there can be no real adherence to the Sermon on the Mount without first recognizing and humbly submitting to the authority of Jesus.
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