"For Luther, as for Erasmus and all earlier Christian hermeneuts, the disposition of the reader remains crucial: we must preface our reading with prayer and continue with the eye of faith, and our faith is thereby strengthened by our reading. But although his is clearly a hermeneutics of faith, it is also actually a hermeneutics of suspicion, at least in principle, for thereby we grow in faith in a typically circular movement from universal faith to particular inquiry and back to universal faith, which is strengthened in the process." - David Jasper, A Short Introduction To Hermeneutics (Louisville: Westminster John Knox, 2004), 59.If Augustine would not stop until he found Christ in the text--by allegory if not in the literal sense, Luther was willing to discard New Testament books, such as James and Revelation, in which he could not see Christ.
My own working approach is to accept the canon on the basis of tradition. I assume the Spirit guided the selection of our 27 NT books, and I accept them as given as a rule of faith. I also happen to like Revelation--not least because of its fantastic visions and images.