For my write-up today on Hans Dieter Betz's Sermon on the Mount, I'll use as a launch-pad Matthew 7:22-23, which states (in the KJV):
"Not every one that saith unto me, Lord, Lord, shall enter into the kingdom of heaven; but he that doeth the will of my Father which is in heaven. Many will say to me in that day, Lord, Lord, have we not prophesied in thy name? and in thy name have cast out devils? and in thy name done many wonderful works? And then will I profess unto them, I never knew you: depart from me, ye that work iniquity."
According to Betz, SM-Jesus (by which I mean the Jesus of the Sermon on the Mount) is talking here about Gentile Christians who do not keep the Torah, for SM-Jesus believes that outside of the Torah there is no salvation. A few days ago, I talked about SM-Jesus' view on the fatherhood of God. Whereas Betz holds that SM-Jesus regards God as Father in the sense that God created all things, which would mean that everyone has God as their Father, Betz backtracks from that position in his comments on Matthew 7:22-23, for he says that SM-Jesus thinks that, at the judgment, only those who follow Jesus' interpretation of the Torah will be able to claim God as their Father. By contrast, the Sermon on the Plain (Luke 6:20-49), which Betz argues is for Gentile Christians, does not root ethics in the Torah, but rather in virtue.
Betz does not believe that the Sermon on the Mount is making heavy-handed Christological statements about Jesus (in contrast to the rest of the Gospel of Matthew, which Betz thinks that the Sermon on the Mount predates), but rather that Jesus in Matthew 7:22-23 is interceding before God as the teacher of his disciples (not as judge or as Christ), as Jesus vouches for those who followed his interpretation of the Torah while not vouching for those who did not. Was there a belief back then that teachers would intercede for their disciples at the last judgment? Betz refers to examples in which Paul appears to think that he will do so, but I cannot find Betz's specific references at the moment. Betz appears to hold that the author of the Sermon on the Mount was aware of higher Christologies, however, for Betz asserts that the Sermon on the Mount is disagreeing with Paul's belief that Gentile Christians are saved because they proclaim that Jesus is Lord (i.e., Romans 10:9).
Although Betz regards the New Testament to be diverse, he does seem to make some attempt to find commonality among the different writings, and also to see how they can complement each other. For example, Betz notes that Paul and the Sermon on the Mount agree on prioritizing love, as well as the need for God's mercy. Betz states that Paul would have a problem with the lack of a redeemer in the Sermon on the Mount, and that Paul would argue that "it is safer in principle to have Christian existence based on Christ's merits than on the uncertain merits of faithful discipleship" (page 555). Betz says that Christ's merits are important, but that "they are inadequate for making everything dependent on them" (page 555).