3:1-3 The apostle urges the Christians in Crete to submit to rulers and authorities. This is a hard bit of instruction, but government officials, employers, and any other persons of authority should be the recipients of our every good work (3:1). In the end, Christians are serving God in all they do, and he is always watching our motives and actions. When we cheat the time clock at work, we are really cheating God himself—and giving the world a poor reflection of our Master.
3:8 Kingdom men and women are to devote themselves to good works. Good works are divinely prescribed actions that benefit others and glorify God (see Matt 5:16). Thus, they are good and profitable for everyone. They bless those in the church, and they bless those outside it by giving them an accurate picture of the love and grace of God and his offer of the free gift of salvation (see Eph 2:8-9).
3:9-11 Meanwhile, kingdom men and women are to avoid foolish debates and quarrels (3:9). Few things drive away seekers like church infighting. So Satan loves to encourage selfish strife and division among church members. What should churches do with a divisive person who quarrels about unprofitable and worthless matters? Warn him twice and then reject him (3:10-11).
In essence, Paul is saying, “Keep to the instructions I have given you and devote yourselves to good works toward all people. If it’s not from the sacred Scriptures, then don’t worry yourselves with it.”