Although the Scriptures don't reveal much about Demas, there are still lessons to be learned from him. Let us consider a few at this time.
1. CHRISTIANS SOMETIMES DON'T APPRECIATE WHAT THEY HAVE IN CHRIST.
The name Demas, short for Demetrius, was a Greek name. Thus, Demas was a Gentile convert to Christianity. When the church was first started, the Gentiles were not included in the gospel outreach. As Ephesians 2:12 teaches, they had been "without Christ, being aliens from the commonwealth of Israel and strangers from the covenants of promise, having no hope, and without God in the world." But, eventually, the gospel plan of salvation was extended to include the Gentiles (cf. Acts 10). Demas surely knew what a great blessing it was that those who had once been excluded were now included. He could rejoice in the fact that in Christ "there is neither Jew nor Greek..." (Gal. 3:27,28). One's race is irrelevant before God.
Sadly, although Demas certainly knew of the blessings of being a Christian, he chose to forsake such for the world. What about followers of Christ today? I'm afraid that there are many who don't understand the manifold spiritual blessings that are theirs to enjoy in Christ (Eph. 1:3). They see the immediate gratification that the world promises and that slowly draws them away from their eternal hope. Be careful, friends, to always cherish the spiritual relationship and blessings that are yours if you're a Christian. If you don't appreciate them, you may later find yourself turning your back upon them--like a dog returning to his own vomit (II Pet. 2:22).
2. NO ONE WILL REMAIN SAVED AGAINST HIS WILL.
Paul was a passionate preacher of the gospel and labored diligently to not only make converts but to keep them saved (cf. Acts 14:22). I can't imagine that Paul didn't do everything within his power to keep his friend Demas faithful to the Lord. However, when all was said and done, Demas followed his own course--he left the Lord.
Sometimes it doesn't matter what we say or do, some brethren fall in love with the world and will not be turned back to the Lord. When this happens, we do have a responsibility to them (cf. II Thess. 3:6ff), but we cannot force them to do the right thing. Such will grieve our hearts (as it certainly did Paul's), but we must press on in spite of the apostasies of our brethren.
3. THE ROAD TO APOSTASTY IS A GRADUAL ONE.
The Bible does not record the details or steps of Demas' apostasy, but it is reasonable to suggest that his falling away was a gradual thing. Usually apostasy is more from neglect than a formal decision to forsake the Lord.
The inspired writer put it this way in Hebrews 2:1-3 - "Therefore we must give the more earnest heed to the things we have heard lest we drift away. For if the word spoken through angels proved steadfast, and every transgression and disobedience received a just reward, how shall we escape if we neglect so great a salvation..."
Paul doesn't give the details of Demas' love for the world. Was he overcome by materialism? Was he tired of a life of self-denial? Did he love his physical life so much that he feared suffering the same earthly fate as Paul? In this realm, we will never know the full story behind Demas' apostasy. But, despite that fact may we endeavor to never follow his example of becoming unfaithful to the Lord!