Enthusiasm for John Wesley’s contemporaries was no less than a dread disease. It was the opposite, even the deadly enemy of rationality, which was for eighteenth-century man the only healthy state of mind.

The Greek from which “enthusiasm” was taken meant possession by a divine spirit. For people who found fulfillment in being possessed in this way, enthusiasm was the most favorable state of existence. For their enemies enthusiasm was a term of ridicule or worse. So it is today.

Meric Casaubon wrote a treatise against the disease of enthusiasm before Wesley’s ministry began. This treatise became a handbook of symptoms of the disease. Other treatises and pamphlets flooded the presses to warn people against enthusiasm.

So when George Whitefield and John Wesley began their ministry, they were called enthusiasts because they preached the Holy Spirit. The majority of people hungered for their appeal to non-rational impulses, but ministers of the Anglican Church, who hated enthusiasm, shut their doors to this renewed appeal to deep spiritual reserves.

For Wesley enthusiasm took many forms, the only acceptable one being the operation of grace in individuals. Wesley was very careful to distinguish this experience from the other kinds of enthusiasm, which were like the forms of hysteria or possession by diabolical spirits.

George Whitefield had a reputation for appealing to all levels and kinds of emotions from the pulpit. Wesley suffered under comparisons to Whitefield. To make matters worse, some of Wesley’s followers exploited the worst kinds of enthusiasm. Wesley himself was criticized by Samuel Johnson, whose rationality was offended by the powerful effects of a sermon delivered by Wesley.

The clearest statement Wesley made on enthusiasm is his sermon On Enthusiasm, which is a balanced assessment: of right enthusiasm against the wrong sorts.