While we are talking about nazis...?

... let's talk about Bonhoeffer. Bonhoeffer said, "If evil appears in the form of light, benefit and renewal, if it confirms with historical necessity and social justice then this, if it is understood straightforwardly, is a clear proof of it's abysmal wickedness". Martha Goebbels described the national socialtist idea as "everything I've ever known to be good, beautiful and true". Can the human mind be deceived about right and wrong, foul and fair? If so, how come?