The Reformation and the Catholic reaction to it caused a massive split within Western Christendom, and further divisions proliferated from that original split. As Diarmaid MacCulloch points out (Reformation: Europe’s House Divided 1490–1700), that is only one part of the story:
“The Protestant communities, which for a variety of reasons and motives cut themselves off from Rome, also cut themselves off from many possible devotional roads to God, because “they saw such routes as part of Roman corruption. In one sense, therefore, the Reformation conflicts stifled diversity. Rome closed down options by the decisions of the Council of Trent: Protestants too were anxious to weed out rival versions of Protestantism where princes and magistrates gave them the chance, and they also rejected many alternatives suggested by more radical spirits. Yet that very cutting- down of options heightens the sense of difference between Catholic and Protestant Europe, because of the rival tidinesses which this process of sifting created.”
Reformers and Catholics both were, in short, simplifiers who inhibited the diversity of late medieval piety and theology, and forged, for all the internal diversity, a great simple divide between Protestant and Catholic.