Now let's start to evaluate the section I've identified from 5:21-48 containing the structured formula. This section actually begins prior to the structures with an announcement of it's intended purpose in verses 5:17-20, an introductory prologue of sorts:
Think not that I have come to abolish the law and the prophets; I have come not to abolish them but to fulfill them.
For truly, I say to you, till heaven and earth pass away, not an iota, not a dot, will pass from the law until all is accomplished. Whoever then relaxes one of the least of these commandments and teaches men so, shall be called least in the kingdom of heaven; but he who does them and teaches them shall be called great in the kingdom of heaven. For I tell you, unless your righteousness exceeds that of the scribes and Pharisees, you will never enter the kingdom of heaven.
The first question we should ask is who is it that is telling Matthew's audience that Jesus, who is speaking here, has come to abolish the law and the prophets? [1] It is of course the Marcionites who preach that Jesus came to destroy the law and the prophets. This verse even elicited a direct and bitter response from which found it's way into Dialogue Adamantius 2.5, stated by the Marcionite champion Marcus: [2]
The Judaizers wrote this, “I did not come to destroy the Law, but to fulfill it,” (Matthew 5:17)
but Christ did not speak this way. He says, “I did not come to fulfill the Law but to destroy it.”
Tertullian explains the purpose of Antithesis in AM 4.6.1, was precisely to separate Christ from the law
For it is certain that the whole aim at which he has strenuously labored even in the drawing up of his Antitheses, centers in this, that he may establish a diversity between the Old and the New Testaments, so that his own Christ may be separate from the Creator, as belonging to this other god, and as alien from the law and the prophets.
Matthew 5:17 is a broadside shot at Marcionite theology and more specifically the cornerstone principle of the Antithesis, that Jesus came to destroy the law and prophets and the works of the creator god, aka "the god of genesis." But it doesn't end there. In the Marcionite gospel we find Luke 16:17 is slightly different, reading λογόι μου instead of τοῦ νόμου
"More easily, therefore, may heaven and earth pass away ... than that one iota of the Lord's words should fail." (Luke 16:17 Marcionite form, slightly paraphrased, Tertullian AM 4.33.9)
Luke 16:17, as part of Luke's central section, was drawn by the Marcionite author from the Time of the Parousia parable of the common synoptic source (Luke 21:32-33, Mark 13:30-32, Matthew 24:34-36 [3]) which reads "Heaven and earth will pass away, but my words will not pass away." That it was Marcionite, and was in view of the author of Matthew 5:18 can be seen by it's proximity to the parable of serving two masters (Luke 16:13), [4] the saying that the law and the prophets ended with John (Luke 16:16), and the Marcionite absolute prohibition on divorce (Luke 16:18). As we shall see these verse in Luke were all in focus of the author of chapter five in Matthew.
Matthew 5:18 is saying that Torah law is still in place, not abolished, as the Marcionites claim,[5] and in fact it cannot be abolished yet, as Christ has yet to accomplish all things. This is also implied in Matthew's (and Mark's) comment about the Parousia, that nobody knows when it will come, not even Jesus the son, only God. [6]
Wee see further in Matthew 5:19 that not only is the Torah not abrogated, but that it is even more strictly enforced, down to every commandment and small ordinance. This is a position in direct opposition to the Marcionites. [7] This is abundantly clear that Matthew is looking at the reference to John in 16:13, as he shows by lifting "the least in the heaven, and the greatest in the heaven" from Luke 7:28, the in the other passage about John in the Marcionite gospel. It is a polemic, taking the absolute opposite position of the Marcionites. Then Matthew doubles down on upholding the Torah, by saying in 5:20 that your righteousness must exceed that of the Pharisees --the Jewish clerics-- to be able to enter the kingdom of the heavens.
Matthew's Jesus thus puts himself up in comparison to the Marcionite Jesus, saying that he upholds every command and minor ordinance, while we know the Marcionite Jesus says he abolished the commands and ordinances. We have a clear framing of the introduction to the formatted sayings which follow, and a clear picture of which sect is the intended target of these rebukes to follow.
Next up three Decalogue saying "pairs"
Notes:
[1] "the law" refers to the books of Moses (Pentateuch or Torah), while "the prophets" to the rest of the OT, not just the books of the prophets, but also the other writings (Job, Psalms, Proverbs, Ruth, et al). Law and prophets is thus short hand for the entire Hebrew bible.
[2] there are too many references to this point in the Patristic writings. One example, Irenaeus AH 1.27.2 state's that Marcion's Jesus came into Judea "manifested in the form of a man" (see Philippians 2:7) so "abolishing the prophets and the law."
[3] Matthew and Mark have add the line "But of that day and hour no one knows, not even the angels of heaven, nor the Son, but the Father only." This suggests a later composition date than the Luke/Marcionite version, as this addition is a response to the delayed Parousia problem.
[4] Serving of two masters is closely associated with the sound and unsound tree parable, as we see Megethius tie together in DA 1.28
'Christ distinctly says, “No [one] can serve two masters.” ... Christ said: “an unsound tree cannot bear good fruit, neither can a sound tree bear bad fruit.”
Tertullian AM 1.2.1 suggests the antithesis began on comparison of Luke 6:43 against Isaiah 45:7 "I am He that created evil," to claim there were two gods, i.e., two masters, one good, the other the creator of evil, which the Marcionites taught.
[5] Marcionites cite Romans 10:4, Epeshians 2:15 and Luke 16:16
[6] This is another important distinction between Matthew's presentation, where Jesus the son is subordinate to the God the father, and that of the Marcionites and also that of the gospel of John, where Jesus has his own powers, in essence equal with the father. (see John 5:18, 10:17-18; see also Galatians 1:1 Marcionite wording "Jesus Christ ... who raised himself from the dead"). This is one element the eventual Catholicism blended in from the heretical movements, that Jesus was also God, and equal part of the trinity. But it was not the position of the early proto-Orthodox.
[7] see Galatians 5:2-4, Epeshians 2:15, among others for the Marcionite position on following the entire Torah