The Case Against Satan by Craig Russell

Before The Exorcist and Rosemary’s Baby, there was The Case Against Satan
 
By the twentieth century, the exorcism had all but vanished, wiped out by modern science and psychology. But Ray Russell—praised by Stephen King and Guillermo del Toro as a sophisticated practitioner of Gothic fiction—resurrected the ritual with his classic 1962 horror novel, The Case Against Satan, giving new rise to the exorcism on page, screen, and even in real life.

Teenager Susan Garth was “a clean-talking sweet little girl” of high school age before she started having “fits”—a sudden aversion to churches and a newfound fondness for vulgarity. Then one night, she strips in front of the parish priest and sinks her nails into his throat. If not madness, then the answer must be demonic possession. To vanquish the Devil, Bishop Crimmings recruits Father Gregory Sargent, a younger priest with a taste for modern ideas and brandy. As the two men fight not just the darkness tormenting Susan but also one another, a soul-chilling revelation lurks in the shadows—one that knows that the darkest evil goes by many names.