2 Timothy 4:9

Demas hath, &c. The Demas here mentioned, is the same that was at Rome with St. Paul in his first voyage, in 61 or 62, and of whom he makes mention in his epistle to the Colossians, (iv. 14.) also in that to Philemon, ver. 24. He was perverted in this last voyage, in 65, and abandoned his master in the time of danger. It is not ascertained whether he entirely renounced his faith, or whether God gave his grace to rise from his fall; or whether the love of the world, with which St. Paul here reproaches him, was only a passing fault, and an effect of pure human infirmity. St. Epiphanius (hæres. 51.) presumes that he renounced the faith, and was engaged in the heresies of Cerintus, Ebion, and others, who held Jesus Christ to be no more than a mere man. Many moderns, Grotius, Menochius, Cornel.[Cornelius a Lapide?], &c. believe that he returned with St. Paul: and Estius himself seems to think that he was the same Demas of which St. Ignatius speaks, writing to the Magnesians, calling him a worthy bishop of God. But this is founded on a false supposition, that this letter was written during his first confinement at Rome, or at least before St. Paul wrote his epistles to the Colossians and to Philemon. (Calmet) --- Loving this world; i.e. his safety, and to avoid persecutions. (Witham)