The Great Disappointment is viewed by some scholars as an example of the psychological phenomenon of cognitive dissonance and True-believer syndrome. The theory was proposed by Leon Festinger to describe the formation of new beliefs and increased proselytizing in order to reduce the tension, or dissonance, that results from failed prophecies. According to the theory, believers experienced tension following the failure of Jesus' reappearance in 1844, which led to a variety of new explanations. The various solutions form a part of the teachings of the different groups that outlived the disappointment.
Both Millerite leaders and followers were left generally bewildered and disillusioned. Responses varied: some continued to look daily for Christ's return, while others predicted different dates—among them April, July, and October 1845. Some theorized that the world had entered the seventh millennium—the "Great Sabbath", and that therefore, the saved should not work. Others acted as children, basing their belief on Jesus' words in Mark 10:15: "Truly, I say to you, whoever does not receive the kingdom of God like a child shall not enter it." Millerite O. J. D. Pickands used Revelation to teach that Christ was now sitting on a white cloud and must be prayed down. Probably the majority, however, simply gave up their beliefs and attempted to rebuild their lives. Some members rejoined their previous denominations. A substantial number joined the Shakers.
This whole period of the Second Great Awakening in US History fascinates me.