Holy Name of Jesus

"Christians are seen to draw their courage, not from incantations, but from the Name of Jesus, and from the commemoration of what He has done. For by His Name it has often happened that demons are put to flight from man, especially as often as they who invoke it, pronounce it with the right disposition, and with all trust. So great indeed is the power of the Name of Jesus, that sometimes it is efficacious even when spoken by the wicked. The Name of Jesus heals the afflicted in mind, puts to flight the spirits of darkness, and to the sick is an ever present remedy."

Origen, Ex Contra Celsus, Bk. 1