Dietrich Bonhoeffer, born in 1906, was executed by the Nazis in the Flossenburg concentration camp on this date in 1945.I did not read much by him when I was younger, but I got the impression that he was a major figure in "liberal" theology, however one wishes to define that.  However, a reading of Eric Metaxas' biography Bonhoeffer:  Pastor, Martyr, Prophet, Spy (Thomas Nelson, 2010) revealed that his theology was in fact quite orthodox and traditional.  This comes  out in chapter 7, which deals with his time at Union Theological Seminary in New York, a postdoctoral year following the receipt of his doctorate in theology from Berlin University.  It seems that Bonhoeffer got more spiritual nourishment at Harlem's Abyssinian Baptist Church, where he taught Sunday school, than in the rarefied atmosphere of Union.  He writes of his experiences in a number of letters which are quoted below.

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There is no theology here [at Union Theological Seminary]...They talk a blue streak without the slightest substantive foundation and with no evidence of any criteria.  The students--on the average twenty-five to thirty years old--are completely clueless with respect to what dogmatics is really about.  They are unfamiliar with even the most basic questions.  They become intoxicated with liberal and humanistic phrases, laugh at the fundamentalists, and yet basically are not even up to their level...

...the lack of seriousness with which the students here speak of God and the world is, to say the least, extremely surprising...Over here one can hardly imagine the innocence with which people on the brink of their ministry, or some of them already in it, ask questions in the seminar for practical theology--for example, whether one should really preach of Christ.  In the end, with some idealism and a bit of cunning, we will be finished even with this--that is their sort of mood.

The theological atmosphere of the Union Theological Seminary is accelerating the process of the secularization of Christianity in America.  Its criticism is directed essentially against the fundamentalists and to a certain extent also against the radical humanists in Chicago; it is healthy and necessary.  But there is no sound basis on which one can rebuild after demolition.  It is carried away with the general collapse.  A seminary in which it can come about that a large number of students laugh out loud in a public lecture at the quoting of a passage from Luther's De servo arbitrio on sin and forgiveness because it seems to them comic has evidently completely forgotten what Christian theology by its very nature stands for...

...Things are not much different in the church.  The sermon has been reduced to parenthetical church remarks about newspaper events.  As long as I've been here, I have heard only one sermon in which you could hear something like a genuine proclamation, and that was delivered by a Negro (indeed, in general I'm increasingly discovering greater religious power and originality in Negroes).  One big question continually attracting my attention in view of these facts is whether one here really can still speak about Christianity....There's no sense to expect the fruits where the Word really is no longer being preached.  But then what becomes of Christianity per se?