Question
What are the Beatitudes? (the "blessed are…" sayings that open the Sermon on the Mount)
Analysis
A picture of the kingdom's people
The Beatitudes are not eight separate rules but a portrait of the kind of person who belongs to God's kingdom, and it runs against the world's scorecard. Those the world overlooks (the poor in spirit, the mourners, the meek) are the ones Jesus calls blessed, and the promises are God's own doing: they will be comforted, satisfied, shown mercy, and shown God. The first and last blessings both promise "the kingdom of heaven" (Matthew 5:3; Matthew 5:10), bracketing the list and making the whole thing about who inherits that kingdom.
They open the Sermon on the Mount
The Beatitudes are the doorway into Jesus' longest block of teaching, the Sermon on the Mount (Matthew 5–Matthew 7), which goes on to the salt and light of the world, the deeper meaning of the commandments, the Lord's Prayer, and "seek first the kingdom of God." Luke records a shorter parallel on "a level place," with four blessings answered by four "woes" (Luke 6:20; Luke 6:24), the same reversal, stated from both sides.
Blessing, not a demand
Read closely, each line is an announcement of grace before it is anything to strive for: Jesus is describing where God's favor already rests. The traits, humility, mercy, purity, peacemaking, are what that favor grows in a person, not entry fees for it. That is why the Beatitudes are usually read as gospel (good news about God's kingdom) rather than a new law to pass or fail.