The correct answer to this open question is the following.
The Protestant Reformation.
1. In 1517, Martin Luther writes his famous document called "95 Theses."
2. Luther's ideas led to the schism or separation from the Catholic Church. This moment is called the Reformation.
3. The Reformation led to a new form of religion called Protestantism. Martin Luther was excommunicated from the Catholic church.
4. The split led to a counter-reformation movement at the core of the Catholic Church.
This was an important moment in the history of modern religion. A German priest, Martin Luther, strongly criticized the Catholic Church hierarchy for its selling of indulgences in exchange for absolving people's sins. That is why he wrote the document "95 Theses" that led to the church Reformation and the following division.