Today's Gospel text is very uncomfortable. Those who reject Christ are here promised eternal judgment. For this reason, the Church must always keep and treasure the Gospel of Jesus Christ in its truth and purity. We stand on this foundation; to neglect it is to reject salvation. The Gospel, exclusive, is the Church's salt - without it, we are no different from the world.
Let no one cause a believer to stumble either. An example: the ELCA's recent actions of condoning the office of the ministry held by practicing homosexuals. This not only attacks the person and work of Jesus Christ, but it also causes some to stumble. Call false doctrine what it is - the hand of the Body of Christ that causes the body to sin - because of the fact, not because we enjoy condemning.
Keep confessing the Truth alone. There is no other name by which we, crucified with Christ, may live. This makes us be separate from the world, not to exalt ourselves, but to keep the saltiness of the Gospel. Keep repenting of sin against the salt. Don't condone false doctrine - but also rejoice wherever the Gospel is proclaimed. "Whoever is not against us is for us." For God works through right doctrine, Christ crucified.
Soli Deo gloria.