Even though Jesus was battling the prevailing Jewish notion that THEY ( only ) were the light of the world ( He may have even been revealing a little subversiveness against the Roman concept here ), His statement rings true today as it did then. It should be noted that much of the reason the world is in the deplorable condition it's in ( arguable, at least ), is that the disciples of the Christ have not done a very good job in following in their Master's exalted footsteps! Immediately, some would most likely object that the Gospel has made great strides in turning this world into a Paradise ( 'back to the Garden' ) & indeed, much of what we call 'growth' has occurred because of Christianity. On the other hand, though, the other side of the coin, so to speak, much has been done in the name of 'God', or 'Christ' that is not only deplorable & despicable, but morally repugnant!
The majority of Christians would most likely argue that the world is in the shape it's in because it belongs to, or is ruled, by the 'devil', or 'Satan'. There is actually some truth to such a statement, since there ARE many 'devils' in this world & the moniker 'Satan' is simply a transliteration of the Hebrew word for 'adversary'! The blame could easily be laid on the shoulders of those who do not follow the Christ & again, they would not be far wrong; a false theology can be found at the root of all the evils that have been & are still being perpetrated in this world, at least those done in the name of 'God'.
'A false theology', I say, because, for one thing, then, like today, Christians were under the assumption that all humanity is under some 'Curse'! Even though, according to Scripture, Jesus the Christ, the Son of 'God' came to break the 'Curse' ( Genesis 3 ), He, again, in this false theology, failed to accomplish this in His ( first ) Parousia & must yet return again, in bodily form, to finish what He started in the first century. Another reason we may posit as 'a false theology' much of what has been known for centuries as Christianity is that the English Bible has been translated from the Greek & Hebrew ( Aramaic ) Scriptures in such a way as to, anachronistically in many cases, force them to be applicable to a different culture & time from what they were originally written.
When Jesus spoke those words, recorded in Matthew 5, to His disciples, His immediate ( direct ) meaning was that they, those who followed Him, were as He was, 'the light ( that ) shines in the darkness' ( John 1:5 ( Psalm 112:4, Isaiah 9:2 & 58:10, ). Again, in the original context, they, as the 'light of the world' were in direct opposition to the Jewish economy of Jesus' Day, 'the darkness'! Although these words were originally spoken to Jesus' disciples in the first century, they apply as well to those who follow in His footsteps today. Contrary to popular opinion though, this exalted moniker applies to non-Christians as well ( better, in some cases ) as Christians!
In order for one to actually BE 'the light of the world', yes, they MUST follow in the footsteps of Jesus! With that said, though, it should be noted that probably as many, maybe more, who do not 'claim the Name', so to speak, actually walk the Path that Jesus walked than some who call themselves 'Christians'! This is not a denunciation of Christianity, though much room for improvement exists on that account; rather, it is to rebuke the prevailing notion that one MUST be a Christian in order to be 'the light of the world'. Neither is this to say that one doesn't have to follow the Path that Jesus walked, though He DID live in a different Time & Culture, for unless one walks as Jesus walked, in kindness & compassion, they will never ( truly ) manifest 'the light of the world', even 'the light ( that ) shines in darkness'!
This Universal Truth must be universally accepted before we can truly move forward! Christians, like the Jews of Jesus' Day, must realize that they alone are not the ONLY 'light of the world': one can follow the Path that Jesus followed, without ascribing to the tenets of Christianity, especially what is known as Christianity today. The Love & Compassion that Jesus showed is not exclusive to Christianity; the choices that individuals make, no matter whether they are Buddhist, Christian, Muslim or Jew, are what determine whether they manifest 'the light of the world', or 'the darkness'!
May we ever choose to manifest the Light!
Charles Haddon Shank