The Reformation was a religious revolution in Western Europe which was largely the result of efforts by Martin Luther, John Calvin, and to a lesser extend, Hulrich Zwingli. All took exception to the established teachings of the Catholic Church, primarily the idea that the Pope was the Vicar of Christ on earth; and that good works were necessary for salvation. Luther's position was that faith alone was necessary; Calvin's position was that all were condemned because of the sin of Adam and Eve; yet God had predestined certain people to be saved. Zwingli's thinking was somewhat similar to Calvin's; although he believed that the second coming of Christ was imminent.
There is little relation between the Reformation and the Age of Expansion, other than once new lands were open to settlement by Europeans, many religious dissidents who were persecuted because of their religious beliefs took refuge in America. The Age of Expansion was largely the result of the Renaissance, a period of rebirth of learning in Western Europe. New techniques of navigation learned from the Muslims made it possible for European mariners to navigate more accurately. This, together with the capture of Constantinople by the Turks in 1453 motivated Europeans to find other routes to the Far East in search of spices, gold, etc. Needless to say, among those searching was Christopher Columbus, who attempted to reach Japan and China by sailing West, but encountered the Americas instead.