There are two basic principles that I have already introduced here but that need to be made as explicit as possible and that we do well to keep in mind as we read the sermon on the mount and the whole Gospel of Matthew.
First, because of the way the Spirit works through human agencies, the text is open to multiple interpretations that may even contradict each other. We have to discern as best we can those interpretations that seem to make the most sense. The dangers are obvious, especially that we simply settle in on an interpretation that is convenient to our own personal ideology irrespective of the intentions of the original compiler/author. There is, however, no getting around this temptation even if (especially if) we choose to think that the text is a holy, infallible text with only one correct interpretation. Thinking that way is a human choice however much those who make it claim that God inspired them to make it. And, truth be told, the infallible-ists still fight like cats and dogs over what they think is the actual one true meaning of the text. The Spirit, rather, works through fallible, broken, gloriously imperfect human agency. We cannot escape our responsibility to read as responsibly and faithfully as we can, each of us. Truth is, reading scripture in this way is a challenge and an opportunity.
Second, part of Matthew's message is the way the author arranged his or her material. Most "readers" of the gospel in ancient times listened to it read aloud as a continuous whole that was not diced and sliced into chapters and verses. The structure of the gospel carried them along, kept their attention, and made important connections for them. We have to pay attention to the arrangement of the gospel if we want to understand what the author intended to communicate through it.
In addition to these two principles, I would like to share a personal thought about the gender of the compiler/author of the gospel. We have no idea who that person was. It was only later tradition that assigned authorship to Matthew, one of the Twelve. Some online searching on the subject of literacy in the Roman Empire suggests that upper class women were likely to be well-educated and literate. Some lower class women, evidently, would also have had some very rudimentary literacy skills. That being the case, it is entirely possible that the author of this gospel was a well-educated, upper class woman follower of Jesus. While New Testament (Koine) Greek was not sophisticated, it is still possible that a wealthier woman compiler/author could have used it to communicate her message about Jesus with the churches, which she would have known were composed largely of the poor. All of this is to say that, however awkward, I will continue to refer to the author as "she or he" / "he or she" in order to preserve the real historical possibility that she was a a woman. (To reinforce this point, I've illustrated this entry with the icon of Saint Nina holding a book rather than the usual one of Matthew. Using her icon makes the point that the author could be a woman.)