As Paul finishes the first chapter of this letter to Titus, he adds a final comment to his description of the false teachers active in Crete. And his opinion is not a good one in the slightest.
You can read his remarks in Titus 1:15-16:
Paul does regard the false teachers very highly at all, and that is apparent as he finishes his description of them to Titus in this chapter. We must remember, the context for this passage is the false teachers. But others have used this passage to justify sinful behavior by ripping it out of its proper context.
Much of the false teachers’ doctrines apparently were centered around the ideas of Jewish ceremonial cleanliness. In the context in which Paul writes this, Paul seems to connect this back to the human commands and Jewish myths mentioned in verse 14. What Paul is definitely not saying is that those who have been purified can engage in sinful behavior and justify it. This is not a license to sin.
In fact, Paul’s point is in the next portion of the very same sentence: “To those who are corrupted and do not believe, nothing is pure.” Here Paul is making a clear distinction between those who have allowed Jesus to make them pure and those who claim to have purity through the Jewish rituals, but actually live sinful and disbelieving lives. This includes both the false teachers and those who have been led astray by their teachings.