In seeking the Scottish Reformation, John Knox made it clear that he was not seeking a political revolution. Instead, he was seeking the reformation of manners and abuses in religion. He understood that the goal of the Reformation was to see the gospel of Christ preached, sacraments administered, and idolatry destroyed. Most of all, Knox understood that the Reformation was God's work by God's people.
This article on church history describes the Reformation in Scotland, which gave birth to Presbyterianism. Through the heritage left by others and the corruption of the Roman Catholic Church, God made sure that John Knox and Andrew Melville had the ground to build on and the opportunity to bring about the Reformation.