That they may adorn the doctrine of God our Savior in all things.
Since Christians are already entitled to heaven and will attain perfection one day in God’s presence, why is spiritual growth necessary? There are a number of reasons.
First, it glorifies God.
Second, it verifies salvation. External change demonstrates an internal change of heart.
Third, it is a good testimony. Spiritual growth puts the truth of God on display for others to see.
Fourth, it provides assurance. When we progress spiritually, we see God at work in our lives, and that helps our confidence in our salvation (2 Pet. 1:10).
Fifth, it spares us unnecessary sorrow. Lack of growth toward godliness results only in pain and sorrow.
Sixth, it protects the cause of Christ from reproach.
And last, it makes us useful for serving in the church.
So continue to grow and be a blessing to those you meet.
that they may adorn the doctrine of God our Savior in every respect. (2:10c)
This last clause in verse 10 is the third purpose clause in this passage that gives a reason for such a call to holy living (see also vv. 5, 8) and, like the one in verse 5, focuses on honoring and glorifying God’ s Word.
Adorn is from kosmeō, from which we get “cosmetics,” the vast array of substances, both natural and artificial, that women (and men) use to make themselves more physically attractive. The root idea of the term is that of arranging something in proper order to give it symmetry, comeliness, and beauty. In ancient times it was used of arranging jewels in a brooch, necklace, ring, or crown in a way that best displayed the beauty of the gems.
Paul of course, was not speaking about physical and superficial adornment. What makes the church attractive and influential in the world for the Lord is not its strategy or its programs but the virtue and holiness of its people. His people therefore are to adorn the doctrine of God our Savior by their submissiveness, by the excellence of their work, by their respectful attitude, by their honesty, and by their loyal service to their employer—whether he is a fellow Christian or a rank pagan, fair or unfair, pleasant or unpleasant, deserving or undeserving.
Our supreme message to the unsaved about God is that He is our Savior and desires to be their Savior as well, because He is “no t wishing for any to perish but for all to come to repentance” (2 Pet. 3:9). We are to let them know—by what we say, by what we do, and by the way we work at our job—that God “is a rewarder of those who seek Him” (Heb. 11:6).
2:10 One of the most obvious differences was that Christians did not succumb to the besetting sin of other slaves, namely, pilfering. The Christian ethic bound them to strict honesty. Is it any wonder that Christian slaves commanded higher prices at public auctions? In general they were taught to show complete and true fidelity. They were to be totally trustworthy and thus adorn the doctrine of God our Savior in every aspect of their lives and service. What was true of Christian bondservants then should be true of all Christian employees today.
 MacArthur, J. (2001). Truth for today : a daily touch of God’s grace (p. 144). Nashville, Tenn.: J. Countryman.
 MacArthur, J. F., Jr. (1996). Titus (pp. 101–102). Chicago: Moody Press.
 MacDonald, W. (1995). Believer’s Bible Commentary: Old and New Testaments. (A. Farstad, Ed.) (p. 2141). Nashville: Thomas Nelson.