As the title indicates, Stephens posits that there was a ‘crisis of belief’ among some groups of Christians during this time period and even as far back as the twelfth century. Stephens believes that this crisis was initiated by the introduction of the works of Aristotle to western Europe via the Arabic scholars of the Islamic Iberian peninsula. Aristotle had taught that the supernatural did not exist and that everything which occurred in the world was the result of natural forces. Christian theologians, most notably St. Thomas Aquinas, attempted to reconcile the teachings of the Church with these rediscovered works of ‘the Philosopher’. The result was the development of natural philosophy, the pursuit of evidence in the natural world that would prove the existence of God.
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In order to acquire evidence of God’s existence, theologians became increasingly interested in encountering supernatural beings or, if all attempts at that failed, other people who had encountered such creatures. The results of this quest were threefold. Exorcism became popular, culminating in the mass possessions of the 1600s. Necromancy, the art of conjuring demons, was practiced by more and more clerics.