Bonhoeffer knew of the betrayal of the church but he spoke of the church as follows:
The church is a piece of the world; forsaken, godless, beneath the curse: vain, evil world–and that to the highest degree because she misuses the name of God, because in her God is made into a plaything, an idol. Indeed, she is an eternally forsaken and anti-Christian piece of the world in that she proudly removes herself from her solidarity with the evil world and lauds her own self. And yet: the church is a piece of qualified world, qualified through God’s revealing, gracious Word, which she is obliged to deliver to the world which God has occupied and which he will never more set free. The church is the presence of God in the world. Really in the world, really the presence of God. (The Form of Chrsit in the World; p. 113)
The author of Ephesians states that Christ loved the church and gave himself up for her “that he might present the church to himself in splendor, without spot or wrinkle or anything of the kind, yes, so that she may be holy and without blemish.” (Ephesians 5:27) Yet we are confronted by the historical fact that the church often fails to reflect even the common decencies of humanity. It is natural for the skeptic to ask whether God made a mistake in first choosing Israel and then the church to be the bearers of God’s revelation to the world. Does Scripture testify to a continued series of failed attempts by God to save the world or are we, in human arrogance, blind to the way of God? Can we learn to exegete the church in a way that allows us to be addressed by Christ?
