Whoever wishes to take up the problem of a Christian ethic must be confronted at once with a demand which is quite without parallel. He must from the outset discard as irrelevant the two questions which, alone, impel him to concern himself with the problem of ethics, "How can I be good?", and "How can I do good?", and instead of these he must ask the utterly and totally different question, "What is the will of God?"
What is of ultimate importance is now no longer that I should become good, or that the condition of the world should be made better by my action, but that the reality of God should show itself everywhere to be the ultimate reality. Where there is faith in God as the ultimate reality, all concern with ethics will have as its starting-point that God shows himself to be good, even if this involves the risk that I myself and the world are not good but thoroughly bad.
The question of good becomes the question of participation in the divine reality which is revealed in Christ. Good is now no longer a valuation of what is, a valuation, for example, of my own being, my outlook or my actions, or of some condition or state in the world. It is no longer a predicate that is assigned to something which is in itself in being. Good is the real itself. It is not the real in the abstract, the real which is detached from the reality of God, but the real which possesses reality only in God. There is no good without the real, for the good is not a general formula, and the real is impossible without the good. The wish to be good consists solely in the longing for what is real in God. A desire to be good for its own sake, as an end in itself, so to speak, or as a vocation in life, falls victim to the irony of unreality. The genuine striving for good now becomes the self -assertiveness of the prig. Good is not in itself an independent theme for life; if it were so it would be the craziest kind of quixotry. Only if we share in reality can we share in good.
"Dietrich Bonhoeffer: Witness to Jesus Christ", pg 233-235