Charles Finney warns revival preachers about the dangers of introducing fanaticism into their ministry, especially when faced with opposition. He emphasizes that bitterness and a censorious spirit can corrupt the revival atmosphere, leading to a loss of love and compassion. Finney reflects on historical examples, including his own experiences, to illustrate how easily a revival can shift from genuine spirituality to fanaticism. He urges preachers to maintain a Christ-like spirit, characterized by gentleness and mercy, to ensure the integrity of their work. Ultimately, he calls for self-awareness and caution in their approach to opposition and criticism.