He that is not with me is against me; and he that gathereth not with me scattereth. Our Lord here is referring to the exorcists, and contrasting their imperfect work with his, showing how hopeless a task it was to attempt to combat the evil one and his satellites apart from him—Christ. It is particularly to be noticed that Jesus neither here nor elsewhere charges these with imposture. Pretence and ridiculous spells and incantations were doubtless constantly mixed up with their attempts to exorcise; indeed, the term used to describe them in Acts 19:13 is one of contempt; but Jesus assumes in his argument here, what was no doubt the fact, that in these cases there was often, in the person of the physician-exorcist, earnestness and prayer mingled with the deepest pity for the unhappy sufferer, and before these there is no doubt that, in the less severe cases of possession, the evil influence or spirit yielded, and for a time at least let go his victim. "See," said the Master, "he that is not with me is against me in this dire conflict against evil;" for these would-be exorcists were utterly unable, even in those instances where they expelled the devil, to render him powerless to do mischief for the future. "My power sent these dread beings to the abyss, there to wait. The would-be exorcists were unable to replace the hellish tenant which they expelled by another and a holier influence. I bring back the once-tormented soul to its old relations with its God-Friend, and replace the unclean spirit by the Holy Spirit." He goes on to say—
When the unclean spirit is gone out of a man, he walketh through dry places, seeking rest; and finding none, he saith, I will return unto my house whence I came out. And when he cometh, he findeth it swept and garnished. The devil, expelled for a season, watches his opportunity and quickly returns; the exorcist-physician was powerless without the aid of Christ to accomplish anything more than a half-cure; the relapse, as we shall see, was worse than the original malady. The imagery of the "dry place" through which the devil walked (luring his temporary absence from the afflicted soul, was derived from the popular tradition that spirits of evil frequented ruins and desert places (see the Talmud, 'Treatise Berachoth,' fol. 3, a; and Tobit 8:3).