## TL;DR

The Protestant Reformation (1517-1648) split Western Christianity. Martin Luther's 95 Theses (1517) challenged Catholic Church practices, especially indulgences. Printing press spread ideas rapidly. Resulted in Protestant churches (Lutheran, Calvinist, Anglican) and Catholic Counter-Reformation (Council of Trent).

## Core Explanation

Luther: faith alone (sola fide), scripture alone (sola scriptura) — rejected papal authority. Calvin: predestination, Geneva model. Henry VIII: English Reformation (1534, Act of Supremacy) — political/ marital, not theological. Wars of Religion: French Wars (1562-98), Thirty Years' War (1618-48, 8 million dead). Peace of Westphalia (1648): established principle of state sovereignty.

## Further Reading

- [The Reformation (Diarmaid MacCulloch)](https://www.penguinrandomhouse.com/books/261409/the-reformation-by-diarmaid-macculloch/)