Demas in Fausset's Bible Dictionary

Contracted from DEMETRIUS, or Demarchus. Paul's "fellow laborer," along with Mark and Luke (Philemon 1:24), and companion (Colossians 4:14) during his first Roman imprisonment. But he declined; for in 2 Timothy 4:10 Paul writes, "Demas hath forsaken (Greek text: "left behind") me, having loved this present world (world course), and is departed unto Thessalonica," probably his home (Chrysostom). Love of worldly ease and home comforts was his snare, a sad contrast to "all them that love Christ's appearing" (2 Timothy 4:8).