Exorkistes derives from exorkizo (to adjure) and denotes one who practiced exorcism by adjuring evil spirits in the name of a higher power. In Acts 19:13, Jewish itinerant exorcists attempted to use Jesus's name as a formula, with disastrous results: the demon replied, 'Jesus I know, and Paul I recognize, but who are you?' and the man overpowered them. The word appears only once in the New Testament.
The failed exorcists of Acts 19 expose a critical theological error: spiritual authority cannot be borrowed or used formulaically. Authority over evil spirits flows from genuine relationship with Jesus, not mere use of His name as an incantation. The sons of Sceva treated 'Jesus' as a magical word; the demon treated it as a test of authenticity. The result was exposure and defeat. This warns against all forms of nominalism — using Christian language without Christian reality. True authority is relational: 'I know Jesus, and Jesus knows me.'