We could call Luke the apostle Paul’s armour bearer. So often he was there, tending to his problems, his very serious health problem.
It is the same with all of us as with Luke. We are all in a great team as a church: every capacity and ability pledged to the Lord’s service and nobody trying to stand head and shoulders above anyone else for self-glory, for self-notice. You can see how this was true of the companions of Paul.
If you find yourself thinking too much about worldly things, loving too much even legitimate, worldly things, aspiring to self-satisfaction in any way, be so careful – even Demas, a companion of Paul, could abandon the mission. Cast yourself upon the Lord and ask for protection and re-commit yourself to him. Will the same as happened to Demas happen to some of us because we underestimate the battle, we underestimate the power and the hostility of Satan and he is watching us to see for the chinks, so that he can turn us back to the world and steal up upon us and cause us to love gain? Demas underestimated the hostility against him and the position and he was brought out of service by the enemy of souls. He would not have lost his salvation, perhaps he would be restored in some way but he forfeited his work and his privileges because he loved this present world.