Colossians 4:14

Paul identified Luke, the writer of the third Gospel and Acts, only as a physician.

"At this time medicine was only just becoming a subject of systematic instruction." [Note: Dunn, p. 283. See The Oxford Classical Dictionary, s. v. "Medicine," p. 662.]

Luke would have been both physically and spiritually helpful to Paul. Demas later forsook Paul (2 Timothy 4:10), but at this time he was ministering to and with the apostle.