J Edwin Orr (1912-1987) 
Historians aren't always the speakers you expect to attract large audiences. But Edwin Orr's expertise was in high demand with churches. For many years an evangelist, he was also a historian of revival--the spiritual renewal of churches. He amassed fascinating anecdotes and worthwhile details about these spiritual movements and 
incorporated them into talks and books. Orr taught that Christians must repent if revival is to flower. "Little by little, the church loses its grip on essential things, becomes a social club, goes to sleep or flies off at a tangent. All over the world we find sleeping churches, and all round them are the gospel-starved masses. Instead of performing the first thing of importance, evangelizing the masses, they are engaged in a bewildering variety of pastimes--anything but the real thing."