Today's Gospel passage from the beginning of the fifth chapter of Matthew opens with a reading of Jesus's Sermon on the Mount, chapters 5-7, which will continue for several Sundays in Ordinary Time. This is the first preaching event after Jesus' baptism and temptation in the desert. Jesus tells the disciples what it means to be counted among the "blessed" in God's kingdom.
Matthew's version contains nine beatitudes while Luke's contains four. A major difference between them is that Luke focuses on the poor, the hungry, and those who mourn, while Matthew broadens these categories. For example, in Matthew it is not simply the poor who are blessed, but the poor in spirit. In all the beatitudes, those who are deemed "blessed" are those favored by God because their suffering in this world will be overturned under the reign of God.