Mark 9:50

“Salt is good. But if the salt has lost its saltness with what will you season it? Have salt in yourselves, and be at peace one with another.”

Jesus then replies to the possible objection which could be raised that salt is good. The connection between this verse and the last is ‘salted' and ‘salt'. But here there is a definite connection with the thought of God's people as being salt, and here it is its purifying quality that is in mind. Compare ‘You are the salt of the world' in Matthew 5:13. Salt was used for preserving and was vital in the ancient world to prevent the putrefaction of food. Thus the idea here is that the people of God are to act as a preservative of righteousness in the world as they love God with all their being and their neighbour as themselves. Such salt is good.

But if the salt loses its saltiness, (as has happened to the one who begins to cause little believers to stumble, it loses its usefulness. How can its saltiness then be restored? The answer expected is, it cannot. It is therefore essential that those who are salt retain their saltiness by a life of trust and obedience, and by dealing violently with sin. And the central nature of that saltiness will be found in their participation in and response to the good news of the Kingly Rule of God now present among them (compare Luke 11:28).

The idea of salt that has lost its saltiness may well have come from knowledge of the salty area around the Dead Sea where deposits which seemed similar to the salt deposits had no saltiness. Although such deposits seemed to be salt it was a waste of time collecting it for it was not salty, while even blocks which were salty could lose their saltiness if something drained the actual salt away.

‘Have salt in yourselves, and be at peace one with another.' Thus He adjured them to retain their saltiness. By retaining their saltiness and remaining firmly established in the covenant and under the Kingly Rule of God, by walking in trust and obedience, they will then ensure that they live at peace with one another. This picture aptly ends a section which began with the disciples arguing about rank. It indicates that if they truly live under the Kingly Rule of God position and precedence will be unimportant, and instead all will be in harmony. What will matter will be purity and peace.