"The idea of being on fire for Christ will strike some people as dangerous emotionalism. 'Surely,' they will say, 'we are not meant to go to extremes? You are not asking us to become hot-gospel fanatics?' Well, wait a minute. It depends what you mean. If by 'fanaticism' you really mean 'wholeheartedness' then Christianity is a fanatical religion and every Christian should be a fanatic. But fanaticism is not wholeheartedness, nor is wholeheartedness fanaticism. Fanaticism is an unreasoning and unintelligent wholeheartedness. It is the running away of the heart with the head. At the end of a statement prepared for a conference on science, philosophy and religion at Princeton University in 1940 came these words: 'Commitment without reflection is fanaticism in action; but reflection without commitment is the paralysis of all action.' What Jesus Christ desires and deserves is the reflection which leads to commitment and the commitment which is born of reflection. This is the meaning of wholeheartedness, of being aflame for God."
John R. W. Stott, What Christ Thinks of the Church, pages 116-117.