Justin Martyr, in his 2 Apology (6), made the following remark, which I found interesting in a number of ways. First, this whole thing about God not having a name. His Christology, as well, is quite developed for his time (fl. 150-160). Then he goes on about the exorcisms, not only about Christians doing exorcisms, but other ways being attempted during that time. I tell you, these ancient Christians are way out of our American evangelical framework.

But to the Father of all, who is unbegotten there is no name given. For by whatever name He be called, He has as His elder the person who gives Him the name. But these words Father, and God, and Creator, and Lord, and Master, are not names, but appellations derived from His good deeds and functions. And His Son, who alone is properly called Son, the Word who also was with Him and was begotten before the works, when at first He created and arranged all things by Him, is called Christ, in reference to His being anointed and God’s ordering all things through Him; this name itself also containing an unknown significance; as also the appellation “God” is not a name, but an opinion implanted in the nature of men of a thing that can hardly be explained. But “Jesus,” His name as man and Saviour, has also significance. For He was made man also, as we before said, having been conceived according to the will of God the Father, for the sake of believing men, and for the destruction of the demons. And now you can learn this from what is under your own observation. For numberless demoniacs throughout the whole world, and in your city, many of our Christian men exorcising them in the name of Jesus Christ, who was crucified under Pontius Pilate, have healed and do heal, rendering helpless and driving the possessing devils out of the men, though they could not be cured by all the other exorcists, and those who used incantations and drugs.