 The movement was first called "Calvinism", referring to John Calvin, by Lutherans who opposed it.Many within the tradition find it either an indescriptive or an inappropriate term and would prefer the word "Reformed" to be used instead.The most important Reformed theologians include Calvin, Zwingli, Martin Bucer, William Farel, Heinrich Bullinger, Peter Martyr Vermigli, Theodore Beza, and John Knox.