There are two versions of the Sermon on the Mount found in Matthew 5:1-11 and Luke 6:20-22.
The Sermon on the Mount contains the most advanced moral and ethical thinking and nothing approaching it can be found in Graeco-Roman thought which. It is only in the Jewish and Christian thought system that such particular emphasis on the poor can be found.
The Sermon on the Mount partakes of poetry. The version in Matthew is longer than the version in Luke. The beatitudes are not a set of moral rules but a speech directing us to the right life and the promises of the kingdom for those who follow the beatitudes. The beatitudes all involved the use of the word “blessed” or “blessing.” In Mathew 5:3, Jesus says the poor in spirit are blessed and theirs will be the kingdom of heaven. Poor in spirit probably refers to humility or weakness, if not poverty. Matthew 5:4 states that those who mourn shall be comforted and are blessed; this probably refers to anyone who is oppressed and, as a result, in mourning. In Matthew 5:5, the meek are pronounced blessed and it is stated that they will inherit the earth. Again this seems to refer to the humble inheriting the earth, meaning entering into the new kingdom to be established by Christ.
The rest of the beatitudes in Matthew 5 are clear and radical in their orientation. In verse 6 we are told that those who hunger and thirst for righteousness in this life shall obtain mercy in the next. In verse 8, again, we are told that the pure in heart are blessed and shall see God, and in verse 9 that the peacemakers are blessed and shall be called sons of God. In verse 10 we are told that those who are persecuted for righteousness sake shall be in the kingdom of God.
As a comment on the Sermon on the Mount and on the beatitudes, most of the beatitudes seem to involve some sort of reciprocity. Jesus says in Matthew 5 that the humble and those who seek after righteousness in this life and those who are merciful in this life, those who are pure in heart and those who are peacemakers and those who are persecuted for their righteousness, shall be rewarded and as it were rule and be fulfilled in the next world.
The beatitudes in Luke 6:20-22 are shorter. I have this to say in particular: in Luke 6:20, Jesus does not say that the poor in spirit are blessed and will have the kingdom of heaven but that the poor ‘will be’ blessed and have the kingdom of heaven. The remainder of the beatitudes in Luke follow to some extent the format in Matthew; they are slightly different yet equally reciprocal. Thus there is the statement in Luke 6:21 that if you hunger now you will be satisfied in the next world and if you weep now you shall laugh in the next. Jesus seems to say here that those in poverty and that those who suffer in this life will rejoice and be satisfied and literally have the kingdom of God in the next. Jesus seem to say in Luke 6:20-22 that those in this life who may seem of no worth and value and suffer the most will be rewarded in the next life above all others. Finally, in verse 22, Jesus states that you are blessed when men hate you and when they exclude you and cast out your name as evil on account of the Son of Man. This last verse tells us that when Christians are persecuted in this world and in this life they will be blessed in the next and even rewarded for their suffering.
The summary here of the main thoughts, thrusts, and teaching by Jesus in the Sermon on the Mount reveals an extremely advanced moral vision and extremely advanced thought in general. Jesus’s teachings in the Sermon on the Mount paints a world and reveals a system of thought far beyond perhaps any contemporary thinking at that time or at any time. Jesus’s statements in the Sermon on the Mount make clear that humility and poverty are somehow blessed and that those in poverty and those who are humble will inherit the kingdom of heaven. This idea will always challenge and disturb the world and its valuation system. There are many teaching in the Sermon on the Mount but this much can be said: that the vision of life presented by Jesus in the Sermon on the Mount represents a radical, if not revolutionary, break from most forms of thinking. We all only know and understand these sayings if we know and understand the God who spoke to Moses from Mount Sinai; the God who spoke to Elijah in the still small voice; the God of the prophets; the God who spoke to Job out of a whirlwind; the God of the agony of Gethsemane; the God of the cross and the God of the empty tomb. These sayings are found nowhere else since they come from Jesus the final and complete revelation of how we may come to know understand God and who he is.