Harmful Idealism

Bohoeffer wrote of a version of legalism that is very subtle because it is a corruption of the true community ideals in scripture:

Innumerable times a whole Christian community has broken down because it had sprung from a wish dream. The serious Christian, set down for the first time in a Christian community, is likely to bring with him a very definite idea of what Christian life together should be and to try to realize it. But God's grace speedily shatters such dreams. Just as surely as God desires to lead us to a knowledge of genuine Christian fellowship, so surely must we be. over­whelmed by a great disillusionment with others, with Chris­tians in general, and, if we are fortunate, with ourselves.
By sheer grace, God will not permit us to live even for a brief period in a dream world. He does not abandon us to those rapturous experiences and lofty moods that come over us like a dream. God is not a God of the emotions but the God of truth. Only that fellowship which faces such dis­illusionment, with all its unhappy and ugly aspects, begins to be what it should be in God's sight, begins to grasp in faith the promise that is given to it. The sooner this shock of disillusionment comes to an individual and to a com­munity the better for both. A community which cannot bear and cannot survive such a crisis, which insists upon keeping its illusion when it should be shattered, permanently loses in that moment the promise of Christian community. Sooner or later it will collapse. Every human wish dream that is injected into the Christian community is a hindrance to genuine community and must be banished if genuine community is to survive. He who loves his dream of a com­munity more than the Christian community itself becomes a destroyer of the latter, even though his personal intentions may be ever so honest and earnest and sacrificial. (Dietrich Bonhoeffer, Life Together)