The initial impulse of the Reformation was directed toward the reforming of belief and church. While the priest as the salvific mediator was indispensable during the Middle Ages, according to Luther, the Christians were to be supposed to comprehend the all-important message of salvation by themselves. Therefore his sola-theology (sola scriptura, sola gratia, sola fide – by scripture alone, by grace alone, by faith alone) had a significant impact on theology and church life. This way, the medieval merit religion was replaced and the decisive role of monasticism, which had been dominant throughout all in the Middle Ages, was broken. The division of labor, that had been predominant until then and according to which a part of the people had to work and serve, while the other part, the “appointees”, prayed for them, was dissolved by Luther's theology.
What Luther intended, was merely a reform within the church, not a reestablishment, let alone a division of the Catholic Church. His criticism of the practice of and abuses that existed in the Catholic Church, like the sale of indulgences and simony, struck a nerve at that time. This criticism proved to be fundamental to such an extent that new churches and new denominations were formed very soon. The most important denominations that emerged from the Reformation were Lutheranism and the Reformed churches.
The Reformation and the subsequent Counter-Reformation lead to a century of religious wars, during which many people died and much of Europe was devastated. Only the Piece of Westphalia in 1648 set an end to the battles among Christians and at the same time strengthened the division of the denominations.