Educated at Oxford University (B.A. from Exeter College, M.A. from Lincoln College), Glanvill was made vicar of Frome in 1662, rector of the Abbey Church at Bath in 1666, and prebendary of Worcester in 1678.
His writings display a variety of beliefs that seem deeply contradictory to contemporary people. On the one hand, he was the author of The Vanity of Dogmatising, which attacked scholasticism and religious persecution and pled for religious toleration, the scientific method, and freedom of thought.
On the other hand, he also wrote Sadducismus Triumphatus, which decried scepticism about the existence and supernatural power of witchcraft. Sadducismus Triumphatus contains a valuable collection of seventeenth century folklore about witches. It deeply influenced Cotton Mather's Wonders of the Invisible World, written to justify the Salem, Massachusetts witchhunt.