We are marching toward the end of Paul’s letter to Titus and in the second to last section, Paul presses deeper into Titus' role as pastor. These four verses have a twofold purpose: 

Titus was to challenge God’s people to maintain good works and do everything necessary to guard against those things that would prevent them from doing good works.

this
ministry:

1. Emphasize maintaining good works

2. Avoid foolish talk

3. Reject willing heretics