This seems to be a good short article on what Luther said about James, Jude and Revelation.
Here is a little quote:
Though this epistle of St. James was rejected by the ancients, 1 I praise it and consider it a good book, because it sets up no doctrines of men but vigorously promulgates the law of God. However, to state my own opinion about it, though without prejudice to anyone, I do not regard it as the writing of an apostle; and my reasons follow.
In the first place it is flatly against St. Paul and all the rest of Scripture in ascribing justification to works. It says that Abraham was justified by his works when he offered his son Isaac; though in Romans 4 St. Paul teaches to the contrary that Abraham was justified apart from works, by his faith alone, before he had offered his son, and proves it by Moses in Genesis 15. Now although this epistle might be helped and an interpretation 2 devised for this justification by works, it cannot be defended in its application to works of Moses' statement in Genesis 15. For Moses is speaking here only of Abraham's faith, and not of his works, as St. Paul demonstrates in Romans 4. This fault, therefore, proves that this epistle is not the work of any apostle.