For Demas hath forsaken me, having loved this present world, and is departed unto Thessalonica; Crescens to Galatia, Titus unto Dalmatia. - 2 Timothy 4:10
I believe I know a little of the grief that Paul felt when he wrote, "Demas hath forsaken me, having loved this PRESENT WORLD." I don't know very much about Demas, but I do know that Paul believed that Demas loved Christ, loved the gospel, and would continue in the faith of Christ until God called him home. But Demas allowed someone or something to come between him and the Lord, revealing that what he had professed for so long was ONLY a profession!
Perhaps Demas had a common, ordinary job and was promoted to a position of authority, which made his association with the despised gospel and apostles embarrassing to him; or perhaps Demas was a widower who met a certain unbelieving, attractive woman, and she turned his foolish head from the church and the gospel; or perhaps Demas came into a great inheritance and his new life-style did not fit the humble life-style of the apostles; or perhaps Demas was a young, handsome man who despised the single life and was determined to marry HIS CHOICE over the protest of the Apostle Paul; or perhaps Demas was an ambitious preacher who felt that toning down the offensive message of free-grace and seeking the approval of arminians and the fellowship of religionists would open doors for him, increase his congregation, and add to his support; or perhaps Demas had just never stopped loving Demas and his claims to Christ were only a part of his effort to promote himself.