Having lectured on Isaiah recently I've come to what I judge is a more satisfying view of the Light of the World & Salt of the Earth passages that commence the Sermon on the Mount.
Traditionally this has been interpreted as the illuminating and purifying effect of the good works of Christians upon the world - either of a conservative or liberal brand.
What has always bothered me about this - though I have preached it myself 3 or 4 times, is that there weren't really any convincing control as to what we make light & salt mean.
I think having recently started to prepare a lecture series on the 5th Gospel, that the Prophet Isaiah has the answer to what this passage really means.
There are a number of factors we should take into account which all seem to fit and line up:
- The text in Matthew is written primarily with a Jewish audience in mind.
- Both light and salt in Isaiah are metaphors for the Covenant in the Old Testament.
- It is hard to imagine that the City on the Hill, given the fact that Matthew above all draws attention to OT theme fulfillment, is not a reference to Mount Zion.
- Isaiah's emphasis on witnesses, which Israel has failed to be, but where Servant Messiah succeeds, has an evangelist bent - they are to go out from Zion, which is exalted above the nations, to spread the Good News as light of God's final second exodus redemptive event.
- David's royal branch, from Jesse's axed-down shoot, is the one who bears worldwide fruit, and summons nations to repent.
- It is His anointing with the Spirit, by which he regenerates, that repentant Jews are pardoned and given a newly created heart to make sure the Law goes forth.
- The Servant of the LORD is made commander of the peoples and a covenant for all nations - all are called to the feast, as newly-illuminated true Jews go forth.
- All of this fits nicely with the way Matthew finishes on the Great Commission - all the nations are called to repent as the Torah issues from Zion.
- Israel is called to be witness to the amazing work of the LORD - despite the fears and doubts, and the exile chastisement, faith in the Covenant promise, absent in King Ahaz, but present in Hezekiah, rests on the Word that, like snow and rain from heaven, cannot proceed from the mouth of the LORD and disappoint or fail to give fruit.
- The fact that light and salt begin the sermon on the mount - with a character description of the true believer's disposition (the Beatitudes) - suggest that Matthew, in contrast with hypocritical Jews (who reject the cornerstone and for whom the Law becomes line-on-line) who do not live the life, is setting out the stall of the sanctified life which is to characterize the followers of Jesus of Nazareth, the Servant of the LORD, as they shine light in the world, as the Covenant People of God.
In other words, the traditional interpretation of the Beatitudes is right, and it is probably also correct to see Jesus as the new Moses. But it is certainly true that He, first and foremost, is the True Light of the World, who as the luminous Servant King in the Line of David, shines God's Glory all around - He is after all, God with us, or Immanuel.
The problem with the people in the days of Isaiah was a failure to live up to the covenant standards of behavior and thus fulfill their putative mission vocation. Of course, in the plan of God, this was all destined from the start. The Exile to Babel was vital to disavow them of their righteousness, exposing the fact that God's Israel was a blind, deaf, ignorant servant, to purge them of idolatry, immorality and iniquity, and help them see, in the Sovereign Work of God, that the Messiah did all, to bring their pride down low, call them to repent, and experience transformation in the knowledge of the light, in order that they may be salt.
It does not of course rule good works out - but it does provide a challenging focus on holiness, which was always the calling of the King of Israel: "Be holy as I AM Holy" which now, in the sermon on the mount, in contrast to superficial rabbinic obedience, becomes a genuine heart obedience, empowered by the Spirit, in morality, piety & relationships: "Be holy in all you do."
This accords, I think, with the other texts of the Old Testament, and keeps good works firmly rooted in the Gospel, and impossible for the liberal who rejects the salt and light of Messiah's atoning work.
Just as a caveat, as these are only some developing thoughts (I actually hadn't intended to publish them today - I posted by accident!) - it is not a hill (excuse the pun) that I would be happy to die on. If it acts as a stimulus to provide a clearer understanding of this marvelous statement in the long run, I'd be content with that. Children of God, remember, you are Salt & Light!