It is the post-millennialist belief that the Second Coming of Christ will occur after the Millennium as a result of Christian success in setting the world morally straight.
Post-millennialist evangelical action was responsible for the abolitionist and temperance campaigns of the last century, and the tenement reforms of 1930's America.
To strive for a society free from moral corruption is an exercise in futility. Such a goal assures eventual frustration, cynicism and a feeling of hopelessness in spiritual redemption. Post-millennialism also breeds fanaticism, and has been shamelessly exploited by those seeking profit from followers desperate for spiritual salvation.