With the Reformation, Luther revived Augustine’s insights. The kingdom of Christ advances exclusively through the Spiritual sword: the Word of God. It is embraced by faith, rather than being coercively imposed by force. In earthly affairs, unbelievers often excel believers. We build temporal cities by our works, but receive the kingdom of Christ through preaching and sacrament.
Horton, Michael; The Gospel Driven Life: Being Good News People in a Bad News World; Baker Books; Grand Rapids, MI; Copyright 2009; page 251
It is striking to me that Luther, Calvin and other reformers – many of whom (like Luther himself) were former monks – did not throw the baby out with the bathwater. Sharply critical of using monastic rituals to ascend the ladder to God, they nevertheless held private as well as public prayer in the highest possible estimation. Luther thought that the busier he was in a given day, the more he needed to prepare for it through earnest prayer and reading of Scripture.
Horton, Michael; The Gospel Driven Life: Being Good News People in a Bad News World; Baker Books; Grand Rapids, MI; Copyright 2009; page 148