The Protestant Reformation began in the 1500s as a response to perceived abuses in the Catholic Church. Martin Luther challenged Catholic doctrine by teaching that salvation came through faith alone, not good deeds, and that the Bible was the sole religious authority rather than the Church. His ideas gained widespread support and formed the basis of Lutheranism. John Calvin also broke from the Catholic Church and established a theocracy in Geneva based on predestination. Calvinism then spread across Europe, though Calvinists faced opposition in some areas.