What does Titus 3:11 mean?

This verse specifies three traits of false teachers. First, false teachers are "warped," from the Greek word exestraptai. This can also be translated as "twisted," or "perverted." Such a person has turned what is good into something evil. Second, false teachers are "sinful." They are not innocently mistaken, but arrogantly, stubbornly, and intentionally promote these incorrect doctrines.

Third is the end result of warped and sinful teaching: the false teacher is self-condemned. It's not necessary for Titus or the local church to proclaim them condemned. They have already condemned themselves. While Titus is to speak against false teachings and false teachers, he does not need to take a false teacher through the process of church discipline (Matthew 18:15–17). The false teacher has condemned himself by promoting teachings which are clearly false, and sinful.

The apostle John mentions an instance similar to this in 3 John 1:9–10. There, he mentions a local leader named Diotrephes, who rejects church authority and disrupts care for missionaries. John's intent is to come to that church, in person, and publicly confront Diotrephes for his errors. False teachers, unlike sincere, but mistaken fellow Christians, are to be directly and publicly rejected.