From Bonhoeffer: Pastor, Martyr, Prophet, Spy, by Eric Metaxas:

"Who stands fast?" he asked. "Only the man whose final standard is not his reason, his principles, his conscience, his freedom or his virtue, but who is ready to sacrifice all this when he is called to obedient and responsible action in faith and in exclusive allegiance to God–the responsible man, who tries to make his whole life an answer to the question and call of God."

This was how Bonhoeffer saw what he was doing. He had theologically redefined the Christian life as something active, not reactive. It had nothing to do with avoiding sin or with merely talking or teaching or believing theological notions or principles or rules or tenets. It had everything to do with living one's whole life in obedience to God's call through action. It did not merely require a mind, but a body too. It was God's call to be fully human, to live as human beings obedient to the one who had made us, which was the fulfillment of our destiny. It was not a cramped, comprised, circupsect life, but as life lived in a kind of wild, joyful, full-throated freedom–that was what it was to obey God. must be more zealous to please God that to avoid sin.  (p. 446)