If someone's possessed by evil spirits, an exorcism probably wouldn't succeed with devilish things of the inexorable kind. To be inexorable is to be steadfast, not easily moved or convinced to budge from a firm or fixed position.
Does the word inexorable have something to do with driving demons out of a person?
From Joseph Conrad's Heart of Darkness: "The brown current ran swiftly out of the heart of darkness, bearing us down towards the sea with twice the speed of our upward progress; and Kurtz's life was running swiftly, too, ebbing, ebbing out of his heart into the sea of inexorable time.
In Henrik Iben's play A Doll's House, Dr. Rank, a victim of tuberculosis of the spine, denounces the "inexorable retribution'' that innocent children must pay for their parent's excesses.
And Henry James writes in The Portrait of a Lady: "The serenity of this announcement struck a chill to the young man's heart; he seemed to see her whirled away into circles from which he was inexorably excluded."