Have you ever noticed the New Testament disciple Demas (Δημᾶς, pronounced day-MAS)? Possibly not, since he only appears three times, at the end of letters.
My mom used to own a collection of Harry Emerson Fosdick's sermons, and in one sermon he made a hypothetical case about the stages of Demas' loss of faith (or, at least, Demas' commitment to Paul's difficult ministry).
Fosdick noted that, in Philemon 23-24, Paul lists him ahead of Luke. Here is the NRSV:
Epaphras, my fellow prisoner in Christ Jesus, sends greetings to you, and so do Mark, Aristarchus, Demas, and Luke, my fellow-workers.
Then in Colossians 4:14, among his greetings and acknowledgments, Paul (assuming Pauline authorship of this letter) mentions Luke first, and then Demas:
Luke, the beloved physician, and Demas greet you.
In 2 Timothy 4:9-11, Paul writes:
Do your best to come to me soon, for Demas, in love with this present world, has deserted me and gone to Thessalonica; Crescens has gone to Galatia, Titus to Dalmatia. Only Luke is with me. Get Mark and bring him with you, for he is useful in my ministry.
Fosdick suggested a regression of Demas' devotion: first he is listed ahead of Luke (implying his importance to Paul), and then he is listed after Luke, implying a drop in importance. In the third verse, Paul regrets that Demas has abandoned him because he loved the world more than the Gospel. (I read that the name is used by John Bunyan for a deceiver in The Pilgrim's Progress.)
Perhaps that isn’t fair. It's not hard to imagine that Paul wasn’t easy to get along with! Paul, like many preachers following him, was singleminded in his efforts. I remember a pastor whom I met casually years ago. He made the comment to someone that Satan had been sending him the wrong persons to assist in his ministry. I thought that was a rather arrogant thing to say. He should have been more humble and said that his assistants had so far been incompatible with his own personality, style, and goals, which does happen in workplaces.
But one’s religious faith and devotion can certainly flag. That's not hard to imagine, either. Many times my faith has become tired and discouraged, especially in the face of difficulties outside my control and times of distress. Tired of feeling worried about certain things, I'm currently seeking God's help to grow in my trust in the Lord.
Thus, in Paul's letters as well as Hebrews and also the Gospels, that we should seek to stay strong in our faith and not to lose heart. Just two passages that come to mind: 2 Cor. 4:16-18 and Gal. 6:9. Can you think of others?
One hopes that Demas found other chances to be a disciple, just as we all hope that God continues to work in our lives when we are weary, or when we drift or stumble.