Martin Luther arguing with Erasmus as to the centrality of the will’s bondage to sin, and therefore the corresponding glory of God’s grace:
Let me tell you, and. . . . let it sink deep into your mind, that I am concerned with a serious, vital, and eternal verity, yea such a fundamental one that it ought to be maintained and defended at the cost of life itself, even though the whole world should not only be thrown into turmoil and fighting but shattered in chaos and reduced to nothing. (Quoted in Steven Ozment, The Age of Reform 1250-1550)
Some doctrines are worth dying for. The truth of the gospel ought to be more precious to us than the tranquility of the world.