Okay, what do we make of the differences between these verses?

First, 3 Nephi has an extra bit of “verily, verily, I say unto you” that is supposed to emphasize the truth of what Jesus says. 

Second, we notice that in Matthew it sounds as if being a light is something we just are, but 3 Nephi shows us that being a light is something that comes from Jesus.  He is the light of the world, and He lights our lights so we can shine to others around us.

A third difference we notice is that in Matthew “the world” is to be lighted with shining example, but in 3 Nephi it is “this people” that is to be lighted.  Part of me wonders if this was personalized to the people of that day.  After all, the Acts of the apostles were written and preserved in the Bible, which has gone throughout the world, but the acts of the disciples in the Americas are not found in the Book of Mormon, so they were only a light to that people.  There is very little preserved in the Book of Mormon of the good example they were from day to day except from very general statements of 4 Nephi that make us wish we could have been there.

We may read it another way if we apply it to ourselves.  Technology and the internet makes it possible to be a light to the world, but very little of we do is going to be broadcast (thank goodness).  Most of the light we shine will be to the people in our lives every day.

Today, let’s try extra hard to be a good example to the people around us.