In an earlier post, we demonstrated that the biblical phrase, “a light into the nations,” does not mean what is popularly thought, that Israel is to set an example for the nations of the world through excellence of behavior, rather it is a call to the prophet Isaiah himself to be a light to the tribes of Israel, who are called “nations.”
However, this phrase appears again in Isaiah 49:6, carrying another meaning.
“I have set you as a light into the nations, that My salvation shall be until the ends of the earth.”
“I have set you as a light unto the nations” — to prophesy regarding the downfall of Babylonia, which is a happiness for the entire world.
Here, according to Rashi, the meaning is that Isaiah’s prophecy is the “light,” bringing joy to the world with his tidings. If so, in this context, “nations” does mean nations of the world, bringing us a step closer to the popularized usage. Nevertheless, the verse still refers to Isaiah himself, not the nation of Israel as a whole, and the “light” refers to a source of joy, not a moral beacon.