While the Beatitudes introduce us to the love of Jesus for the poor and the meek of this world, the two homely metaphors which follow – “salt of the earth, light of the world” – indicate the disciples’ exemplary role in bringing about the new reign of God.
The metaphors of salt and light are easily grasped. Salt is something that seasons and preserves food. Light dispels the darkness. By his good works, the disciple is meant to bring taste and flavour to ordinary life and become a source of enlightenment to those who seek the truth. The two metaphors encourage a leadership role in Jesus’s disciples. Living up to the ideals of the reign of God, they will transform society.
But what if the disciple doesn’t live up to his promise? Like salt that has lost its savour, the disciple too will be set aside and rejected. Or to take the other simile, instead of lighting up the house, this lamp will be concealed under a tub, its glow suppressed.
The Sermon on the Mount presents ideals which are lofty and sublime. They are framed in the context of the Jewish Law, but rise far above it in the challenges Jesus places before those who would follow him.