The Greek noun energeia refers to working, operation, or effective power — the active, producing activity of a force or person. It is the source of the English word 'energy.' Paul uses it exclusively of either divine power or Satanic deception in the New Testament.
Energeia in Paul describes power that is operative, not merely potential. In Ephesians 1:19, Paul prays that believers would know 'his incomparably great power... the working (energeia) of his mighty strength' — the same power that raised Christ from the dead. In Philippians 3:21, the Lord will transform our lowly bodies 'by the energeia by which he is able to subject everything to himself.' Remarkably, Paul also uses energeia for Satanic deception (2 Thessalonians 2:9, 11) — the 'working of Satan' and the 'working of delusion.' This parallel reminds us that spiritual power is not neutral; it is always in service of either the Kingdom of God or the kingdom of darkness. The believer's confidence is in the superior energeia of God.