Calvin had no weapon but the Bible. . . . Calvin preached from the Bible every day, and under the power of that preaching the city began to be transformed. As the people of Geneva acquired knowledge of God’s Word and were changed by it, the city became, as John Knox called it later, a New Jerusalem from which the gospel spread to the rest of Europe, England, and the New World.
(James Montgomery Boice, quoted in The Expository Genuis of John Calvin by Steven Lawson)