Classifying Bonhoeffer in today's terms as a 'liberal' or a 'conservative' (politically) does not fit the man or honor the humanity of the man. He saw the humanity in all equally be they Jewish, or Black.
His time spent in NY, where he regularly attended church in Harlem, the fact he sought out Black Gospel records and took them with him back to Germany, shows that the man is not easily categorized. He honored the Bible, he honored God and in his short life, he honored humanity.
The reason Bonhoeffer made a point to attend a Harlem Church service is because he was disgusted with midtown’s liberal Rockefeller-backed Union Theological Seminary on Broadway at 121st Street.
Bonhoeffer was a conservative. It is a label but it fits him just like the label Christian. Both labels are imperfect and both describe many that are very different than Bonhoeffer but confined as we are to the bottleneck of the English language it is still proper and wise to use labels. It does not dishonor him.
If I knew nothing about Bonhoeffer other than his writings in THE COST OF DICIPLESHIP, I would still recognize him as a Conservative.