For Lutherans the great read has to be “The Hammer of God” by Bo Giertz.  Sadly the original has been badly served by American translators who all but excised Giertz’s defense of Confessional Lutheranism and his attack on a watered down version of Christianity.  Yet there is some good stuff left.

“Read God’s Word now as God’s Word, without skipping anything. Underline heavily everything about what our Savior has done for us. And if you like, write ‘For me’ in the margin. You need this yourself, and it is your duty to preach it to your congregation, as well.”
Bo Giertz, Hammer of God