He wasn’t an ordinary monk. For a start, he had a tendency
to swear. Church historians are divided as to whether this was simply his rough
upbringing or deliberate in order to shock the establishment. Maybe both.
His moment came as he read the book of Romans- you can read about it here. It changed him. And it changed the world. He spoke of salvation
by faith alone- so different to the salvation by works message from the Pope.

Luther was a man whose message changed the world. Because of
him we have the Protestant church streams, we have the Reformation, we have
genuine faith in Christ. What an influence.
Read more:
Convinced by Scripture, Andy Johnston