How will the disciples become salty? In the context, to become salty is to live out the Beatitudes. To be poor in spirit is to be salty in this world. To mourn for sin is to be salty. To be meek against oppression is to be salty in this world. To hunger for righteousness is to be salty. To be merciful to the poor is to be salty in this world. To be pure in heart is to be salty. To be a peacemaker is to be salty in this world.
Jesus said, “But if salt has lost its taste, how shall its saltiness be restored” (Matt. 5:13)? How can salt lose its saltiness? It’s like saying that water can lose its “water-ness.” Pure salt cannot lose its taste of salt. But in the time of Jesus, salt was not real salt. The salt that was sold was often mixed with other minerals. In humid weather, it would evaporate, leaving a residue of lime. This lime or gypsum is mistaken as salt. The residue of lime or gypsum no longer tastes as salty as salt. In this way, the salt has lost its saltiness.
“If salt has lost its taste, how shall its saltiness be restored?” The word, “restored” (moraino), means, “become foolish.” (Gingrich) Jesus is saying that to lose your saltiness is to become foolish. To become foolish is to lose your value, to lose your impact, to lose your significance, or to lose your effectiveness in this world.
How do we lose our impact in this world? Well, when you join your friends in their sinful lifestyle. When you get drunk like they do, you become one like them. When you are as dishonest and greedy as they are. When you sin as they sin. Or when you just keep quiet while they are robbing the bank. That is when you lose your impact for God in this world.
We therefore make fools out of ourselves. We claim to be people of the kingdom of light. But we live like people of the kingdom of darkness. What else can be more foolish than that?
Then Jesus said in v. 13, “It is no longer good for anything except to be thrown out and trampled under people’s feet.” In those days, people throw useless salt on the ground. Salt hardens the ground. People would then trample on the salted ground.
Jesus does not mean that unsalted disciples lose their salvation. Matthew is not writing about salvation. He is writing about living as people of the Kingdom. Jesus is saying that tasteless disciples are useless disciples. God can no longer use them. God sets them aside. It can also mean that people simply reject their testimony. You behave like them. There is no longer something different with you anymore. Your testimony is no longer significant for them. So they reject your testimony.