The last two sentences of Trueman's short post are extremely helpful!!!! I've been criticized for reading Bonhoeffer, and other, and this is how I've tried to explain my interest in occasionally reading those who's theology differs at points from my own.
Trueman says it well: "Sometimes the problem derives from us asking a fundamentally wrong-headed question. Of more value than `Was he an evangelical?' is surely `How can I learn from him how better to be a Christian?'"
I'm sure that some folks will find a reason to criticize even Trueman's posture towards reading non-evangelical theologians, but I believe that there is wisdom in this perspective.
BTW, I recently received a copy of Mataxes' biography of Bonhoeffer and would love to dig into, but I just began a new seminary class (with RTS) and all of my general reading is going to have to take a back seat to Berkhof, Calvin, and Murray.