Who is Matthew's intended audience for the Sermon on the Mount?

Question

On another question, I've received several answers to the effect that the ethical teachings of the Sermon on the Mount aren't terribly relevant to Christians— that they were given to people under the old covenant in order to lead them to the new covenant. Certainly some of the ethical teachings of the Sermon seem an impossibly high bar to follow.

Does Matthew expect Jesus' disciples (post-narrative) to live up to the standards set in the Sermon? In other words, is the Sermon for Christians? Or is the purpose of the Sermon to raise the bar of the law so high that the only recourse left to the hearer is to plea to the judge for mercy? Or in other words, is the Sermon for those who do not believe?

Answer 1

The Sermon on the Mount begins with the beatitudes, the first of which sets the context for the whole sermon.

Blessed are the poor in spirit, For theirs is the kingdom of heaven.
-- Matthew 5:3

Who are the poor in spirit? Well, anyone who is spiritually needy, of course. Those who know they're lives are becalmed and need some "wind" in their sails to get them moving. Jesus identifies these needy ones as the mourners, and the meek, and the hungry and thirsty for righteousness.

Those who don't mourn are rich and have no need of comfort. But, if they don't exercise mercy then they will never know the mercy of God.

Those who have great power make themselves rich by taking the earth. But, if they're not making peace then they will forever stand outside the family of God.

Those who consider themselves righteous are already rich. But if they're not pure in heart they will never stand in the presence of God.

Lay not up for yourselves treasures upon earth, where moth and rust doth corrupt, and where thieves break through and steal: But lay up for yourselves treasures in heaven, where neither moth nor rust doth corrupt, and where thieves do not break through nor steal: For where your treasure is, there will your heart be also. ...

Therefore take no thought, saying, What shall we eat? or, What shall we drink? or, Wherewithal shall we be clothed? (For after all these things do the Gentiles seek:) for your heavenly Father knoweth that ye have need of all these things. But seek ye first the kingdom of God, and his righteousness; and all these things shall be added unto you.
-- Matthew 6:19-21,31-33 (KJV)

I counsel thee to buy of me gold tried in the fire, that thou mayest be rich; and white raiment, that thou mayest be clothed, and that the shame of thy nakedness do not appear; and anoint thine eyes with eyesalve, that thou mayest see.
-- Revelation 3:18 (KJV)

Conclusion

The Sermon on the Mount opens with an advertisement -- an advertisement for the treasures of heaven, and Jesus is the doorway into the treasure house. Jesus' audience, then, consists of anyone who is interested in buying what he has to sell.

Answer 2

Research: Jesus and the Victory of God; How God Became King; Simply Jesus; all by N.T. Wright. There are many other books that speak to the same topic and answer the same questions by other authors as well.

Answer from research: Multilayered, of course, yet the entire Bible, especially the Old Testament/Tanak is profitable for learning. (Romans 15:4) So, the Sermon on the Mount and the Sermon on the Plain, neither of which is titled in this way, are insight into the nature of the kingdom of God, Jesus' primary topic in the Gospels. Understanding the nature of the kingdom is key to understanding the entire narrative of Scripture. God rules dianthropically (through humanity) to accomplish the purposes of letting creation flourish. Obviously, humanity chooses to be ruled by sin and idolatry. However, God's plan to redeem is not cast off. Jesus is the human one who accomplishes and continues to accomplish God's sovereign will. Humanity, regardless of social rank or even awareness, is called into this will.

The Sermon on the Mount is not a replacement of the Law (Torah). Paul teaches Galatian believers that Torah is the tutor which leads to Christ (Galatians 3:24ff). The Sermon on the Mount is akin to an inaugural address, stating that God's kingdom over the nations is emerging even though Israel remains in covenant exile and is ruled by bestial empires (cf. Deuteronomy 28:1 and Daniel 7).

1. Israel recalls blessings and cursing from Moses in Deuteronomy 28-30 when the crowds and disciples hear the SOTM. These are life for Israel and death for Israel when Moses repeats the terms of the covenant. Israel is to choose life in order to be transformed by wisdom into God's holy nation. They once enjoyed being a nation but have since been cast out due to sin and idolatry. Nevertheless, God has not abandoned his promises about redemption. Jesus, in Matthew, is the Deut. 18:15-18 promised one whom Israel shall hear as their ultimate deliverer. Jesus, in Matthew has 5 discourses like Moses has 5 sections of Torah. Jesus begins with "blessed" ashre (Hebrew) which is translated into makarios (Greek). Ashre is living with an understanding of that which Jesus has brought into reality, a mode of life (eternal life), which is understood as genuine blessedness. Jesus brings a new lens into human history, through which anyone can see God. The external appearance of blessing defined by Jesus' culture is not the kingdom definition. It matters not what we imagine of others in regard to God's blessedness within our lives. Our perspective is what matters and what must be in alignment with God. Jesus' hyperbolic method of proclaiming these truths is the content of the SOTM.

2. Jesus begins with news of the kingdom which has finally appeared as promised and those to whom it is coming are characterized in the 9 blessings. They are not the powerful and influential in their society, or those who imagine that the kingdom is to be given to Israel through violence. Those who are receiving the kingdom are recognizing that Jesus is Israel's king and deliverer. Jesus is not offering better advice. He is characterizing the nature of the kingdom as it is being launched or introduced to Israel through Himself as their "greater than Moses" covenant bringer. Matthew 23 concludes with the woes or cursing upon the type of life perspective that will not inherit the kingdom.

3. Concluding, the SOTM encapsulates the same theological treasures as those similarly described in the other Gospels and referred to by the rest of the New Testament. A believer is interested in the news that changes the way the entire world understands the past, present and future. In the SOTM, Jesus presents this new covenant lens through which blindness can become sight. If the SOTM is merely ethical Everesting for assurance purposes (and it is not) then climbing is never without fear and doubt. Sadly, our generation is repeatedly misinterpreting Biblical soteriology. We cannot atone for our sins. This misses the point and is answered for the crowds who listen to the SOTM. Jesus isn't replacing the law (Matthew 5:17) and also isn't introducing a different moral standard. Jesus is creating a new period of history and the way into it is through trusting him.