Orthonorm is right, it depends whether or not Luther's anti-semitism was an integral part of his thought, or whether it was just "tacked on," so to speak. In the latter case, it is clear that one could safely ignore it without compromising the integrity of his thought, but if the former, then we could not reject it without also rejecting everything else that he taught.
This is what I have been saying about Aquinas. What is most valuable is not so much his theological conclusions (as worthy as most of them are) as his method and general metaphysics. You cannot reject the metaphysics and method without rejecting his whole corpus of writings, for it grounds them all, but you can reject certain of his conclusions, without having to write him off altogether.
Actually I disagree. I think someone could accept certain of Aquinas' conclusions (especially if they are based upon common Patristic tradition), while simultaneously rejecting his Aristotelian methodology and metaphysics. In fact, St. Gregory of Nyssa went out of his way to belittle the pagan philosophy of the Greeks when it came to dealing with theology (see for example his treatise "The Life of Moses," and his "Commentaries on Ecclesiastes"), because for him the so-called "wisdom" of the Greeks cannot tell us anything about God, but it may be useful when looking at creation (see also the sections on philosophy by St. Gregory Palamas in "The Triads"). St. Thomas, as I see it, simply misapplied the philosophical categories of the Greek pagans to God, when he should have known that such things could never allow him to truly transcend the gap between the created and the uncreated.
That said, is there a place for Aristotle in looking at the created world? Sure, I do not see anything wrong with that.
Is there a place for his philosophy when coming into contact with God? No, I do not think so.