The Greek verb diamachomai (διαμάχομαι) means to fight through, to contend vigorously, or to argue strenuously. The prefix dia intensifies the root machomai (to fight/quarrel), suggesting a fight carried through to completion. It appears in Acts 23:9, where the scribes of the Pharisees party 'strenuously contended (diamachomai)' in Paul's defense against the Sadducees.
Acts 23:9 shows an unexpected moment: the Pharisees, Paul's theological opponents, actually fought on his behalf against the Sadducees because Paul had skillfully invoked the resurrection — a doctrine the Pharisees shared with him. Diamachomai here captures intense, earnest advocacy. This echoes Jude's call to 'contend earnestly (epagōnizomai) for the faith' (Jude 3). The Christian life is not passive — it requires vigorous contending for truth, even when that means unexpected alliances and strategic boldness. Paul's wisdom before the Sanhedrin shows that faithful contending includes tactical intelligence.