For whatever departs from the word of God (which is the only way, as Christ says, “I am the way, and the truth, and the life” [John 14:6]), however well and beautifully it may glitter, is without question error, lie, and death. It is without the word of God, that is, without the way, the truth, and the life. And what need would we have of the word if we could find ways for ourselves without it? For the word alone is the lamp to our feet, and the light to our path [Ps. 119:105], which, as St. Peter says, shines in the darkest place of this world [II Pet. 1:19]. Whoever does not hold it constantly and steadfastly before his eyes—where else can he go but into darkness? The light therefore is there in the darkness so that we can guide ourselves by it.
Now let us look in turn at each of these new things which have arisen in the pope’s new church. We discover that they have all been invented without God’s word, that is, without the way, the truth, and the light, but rather out of human devotion or opinion, or the malice of the pope. Therefore, as the church of the pope is full of indulgences, human merit, brotherhoods, worship of saints, monkery, masses, satisfaction, and the things we have already mentioned, such as worship, it is full of error, falsehood, idolatry, unbelief, murder, and is the epitome of the church of all the devils. They cannot say that God’s word teaches such things. (Luther’s Works, v.41, p.215)