To TEACH A DIFFERENT DOCTRINE — heteros, 'other, different', + didaskō, 'to teach'; a compound almost certainly coined for the Pastoral letters, where it appears only twice (1 Timothy 1:3; 6:3) and nowhere in Greek before them. ⚠ It is the occasion of the whole letter: Timothy is left at Ephesus precisely to 'command certain persons not to heterodidaskalein'. The error is never spelled out — the readers knew it — but the word frames it as teaching that is simply OTHER than the received deposit, a deviation rather than a rival system. The heteros- prefix is the same one behind Paul's 'a DIFFERENT gospel, which is no gospel at all' (Galatians 1:6). → first discussed at 1 Timothy 1:3