Revivalism assumes that the normal Christian life is one of decline. Left to themselves, Christians will backslide. Therefore, Christian living becomes an oscillation between habitual backsliding and moments of revival or "getting right with God." The turning point from backsliding to revival is typically a crisis decision, and the main responsibility of the preacher is to produce these crises. He does this by means of "hard preaching," which focuses on the plan of salvation, the importance of soul-winning, and whatever rules of conduct the backslider is presumed to be violating. A person who wishes to get right with God usually communicates this crisis decision by "going to the alter." 
So, that's what it is. But what exactly is the problem with revivalism? Well, according to Bauder, there are at least eight of them.
Revivalism produces several consequences. First, by emphasizing crisis decisions, it works against the notion that the normal Christian life is one of incremental growth. Second, it downplays or rejects the importance of biblical exposistion in preaching, substituting confrontational exhortation. Third, it amplifies soul-winning as the key feature of being "right with God." Fourth, it lends itself to externalism: the spirituality of any believer can be judged by conduct, and the effectiveness of any minister can be judged by the number of decisions that are made under his ministry. Fifth, it fosters a philosophy of leadership that puts pastors in a near-dictatorial position (if the normal Christian life is one of decline, then important spiritual decisions cannot be left to ordinary Christians). Sixth, since numerical results are crucial, revivalistic churches tend to adopt methods that are calculated to draw crowds. Seventh, in these churches, congregational worship is depreciated or repudiated. Eigth, revivalism downplays the importance of theology and, consequently, of theological education. 
Living in the Bible-belt, and having attended church all my life, I have witnessed all these errors first-hand. I have friends and family who live in a constant state of spiritual malnourishment due to the fact that the local churches they attend are infected by this cancer called revivalism. It grieves my soul.
I want to make one thing clear, though. I don't hate revivalists. Many of them are dear brothers in Christ. It's their methods I hate. As far as I can tell, most of those whose ministries could be characterized as revivalistic dearly love the Lord and desire to do his will. Yet, the sad fact is, though they may be doing the Lord's work, they are not doing it the Lord's way. It's my prayer that someday they'll join me in rejecting counterfeit revival in favor of the real thing.
1. Kevin T. Bauder, "Fundamentalism" in Four Views on the Spectrum of Evangelicalism, edited by Andrew David Naselli and Colin Hansen, (Grand Rapids, MI: Zondervan, 2011), p. 42.
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