Martin Luther has many claims to fame. In recent years I have found him useful in an unexpected way: as a guide to understanding emerging African Christianity. Here is my unscientific rule: if Martin Luther treated a biblical book with disdain or outright hostility, then that book is really popular in modern Africa.
As a Bible scholar, Luther was a perceptive and quite daring critic. He tested the authority of books by their claims to apostolic authority and judged their faithfulness against what he considered the core teachings of the earliest church. By this standard, he argued that four New Testament books in particular—Revelation, Hebrews, James and Jude—fell short of true canonical status and should be printed separately in future versions of the Bible.