from National Review:
LOPEZ: What are the most prevalent myths about him?
METAXAS: One of the big ones is that he was a pacifist, which he wasn’t. But the Sixties anti-war movement appropriated Bonhoeffer for their purposes nonetheless. They seemed to be under the impression that, had he lived, he would have been the third person in bed with John and Yoko. Another myth about him is that he was an advocate of income-redistributionist “social justice.” There’s just no actual evidence for that.
But the main myth about him is that while imprisoned by the Gestapo he drifted away from orthodox Christianity toward some kind of “post-Christian humanism,” that he became some kind of atheist. This one is based off of a single infamous phrase — “religionless Christianity” — that he wrote in a letter to his best friend Eberhard Bethge. It turns out that Bonhoeffer meant precisely the opposite of what the atheists and agnostics said he meant. This is a classic case of the lie traveling around the world four times before the truth gets a chance to put its shoes on. There was no rebuttal to this misinterpretation for so long that it just got out there as a fact and stayed out there — basically until now, over 50 years later.