In The Epistle to the Romans, Barth writes the following concerning the false image of God at the heart of religion:
What men on this side resurrection name ‘God’ is most characteristically not God. Their ‘God’ does not redeem his creation, but allows free course to the unrighteousness of men; does not declare himself to be God, but is the complete affirmation of the course of the world and of men as it is. This is intolerable, for, in spite of the highest honours we offer him for his adornment, he is, in fact, ‘No-God’. The cry of revolt against such a god is nearer the truth than is the sophistry with which men attempt to justify him (Romans, 40).
Indeed, for Barth, the quicker the enterprise of worshipping the “No-God” runs aground, the better, for only after we have been disabused of our false god will we be ready to encounter the true God.
This is similar to Bonhoeffer, who, writing to Bethge on July 16, 1944, says:
This is the crucial distinction between Christianity and all religions. Human religiosity directs people in need to the power of God in the world, God as deus ex machina. The Bible directs people toward the powerlessness and the suffering of God; only the suffering God can help. To this extent, one may say that the previously described development toward the world’s coming of age, which has cleared the way by eliminating a false notion of God, frees us to see the God of the p 480 Bible, who gains ground and power in the world by being powerless (Letters and Papers from Prison, DBWE 8:479-480).
Both Barth and Bonhoeffer thought that the elimination of a false notion of God was a good thing, even if it did not appear to be a good thing, because such an elimination was a preparation to encounter the true God.
However, Barth and Bonhoeffer differed in their descriptions of the false gods that humans are prone to create and worship.
For Barth in Romans, the ‘No-God’ is revealed to be a false god because he merely affirms the course of world history and the unrighteous desires of human beings, without judgment and without redemption.
However, for Bonhoeffer in Letters and Papers from Prison, the false god is revealed to be false because he is a god of power/strength, the projected opposite of human weakness, whereas the God of the Bible is a God who (1) can affirm human strength and (2) redeems through weakness and suffering, as seen in the life of Jesus.
Furthermore, for Barth the “No-God” is able to be known directly, he is close at hand, whereas the true God is hidden even in the midst of his self-revelation, never able to be known or grasped directly. (See, e.g., Romans, 38, 51.)
However, for Bonhoeffer, even early in his career, “God is present, that is, not in eternal nonobjectivity but—to put it quite provisionally for now—‘haveable’ [,habbar‘], graspable in the Word within the church” (Act and Being, DBWE 2:91).
In Letters and Papers from Prison, it is the false God that is distant, encountering human beings only at the border [Grenze] of their possibilities. The true God, for Bonhoeffer, always encounters human beings in the center [Mitte] of their lives.