Furthermore, to put aside all kind of works, even contemplation, meditation, and all that the soul can do, does not help. One thing, and only one thing, is necessary for Christian life, righteousness, and freedom. That one thing is the most holy Word of God, the gospel of Christ, as Christ says, John 11:25, “I am the resurrection and the life; he who believes in me, though he die, yet shall he live”; and John 8:36, “So if the Son makes you free, you will be free indeed”; and Matthew 4:4, “Man shall not live by bread alone, but by every word that proceeds from the mouth of God.” Let us consider it certain and firmly established that the soul can do without anything except the Word of God and that where the Word of God is missing there is no help at all for the soul. If it has the Word of God it is rich and lacks nothing since it is the Word of life, truth, light, peace, righteousness, salvation, joy, liberty, wisdom, power, grace, glory, and of every incalculable blessing.
– Martin Luther, On Christian Liberty (Trans. W.A. Lambert; Minneapolis, MI: Fortress Press, 2003), 5-6.