There’s an interesting note in the NET Bible about Matthew 5:13. The passage is this one:
5:13 “You are the salt 13 of the earth. But if salt loses its flavor, 14 how can it be made salty again? It is no longer good for anything except to be thrown out and trampled on by people. 5:14 You are the light of the world. A city located on a hill cannot be hidden. 5:15 People 15 do not light a lamp and put it under a basket 16 but on a lampstand, and it gives light to all in the house. 5:16 In the same way, let your light shine before people, so that they can see your good deeds and give honor to your Father in heaven. (Matthew 5:13-16 NET Bible)
The thought that struck me is that salt can’t lose its flavor. You are the salt of the earth, and salt cannot lose its flavor. You are a city on hill, and you cannot be hidden. You are the light of the world, and a light gives light to all. There isn’t any “if” or “but” other than rhetorically. The fact that salt does not lose its flavor is the point.
There is no such thing as undercover Christ-followers. You cannot be a disciple of Jesus and not be the flavorful salt of the earth, any more than you can have faith without evidence in action. Salt is either salty, or its not salt.