Useful, profitable, serviceable — literally 'well-used' or 'easy to use.' Paul applies this word to people: Mark, once rejected by Paul as useless for ministry, is later declared euchrestos — useful. In 2 Timothy 2:21, the believer who purifies themselves becomes a vessel 'useful to the Master.'
Euchrestos tells the story of redemption and restoration in miniature. Mark was once achrestos (useless) in Paul's eyes — he had deserted them in Pamphylia (Acts 15:38). Years later, Paul writes: 'Get Mark and bring him to me, because he is euchrestos to me' (2 Timothy 4:11). People who fail are not finished. God specializes in turning the useless into the useful, the rejected into the indispensable.