If you grew up Catholic and visited a Protestant church, you might be surprised to see that they use a different Bible. But it’s not for the reason you might think. Understanding why they differ, tells you something important about these two churches.

In 1505, Martin Luther was returning home after having started studies in law, when he found himself in a thunderstorm that made him fear for his life. He sought shelter by a large rock and famously cried out, “Help me, Saint Anne, and I will become a monk.” Luther was spared any harm and he returned home, had a party with his friends, and entered a monastery never to study law again. He later came to reflect on this moment and was convicted that he was wrong in treating Saint Anne in a way that he was convinced only God should be treated. This remains a point of disagreement between Catholics and Protestants to this day.

Protestants believe that salvation is found in Jesus alone. Catholics teach that Mary is the “Helper.” Protestants believe that there is only one mediator between God and men. Catholics teach that there’s a Mediator and a “Mediatrix.” Where have you put your faith? Who are you trusting to save you? Is Jesus alone the solution or is Jesus just part of the solution?

Many Protestants assume that Catholics teach that you need faith and works to be saved. Catholics, similarly, often assume that Protestants teach that works are irrelevant to salvation. The reality for both is more nuanced.

Both Catholics and Protestants see Jesus as central to forgiveness and salvation. They differ, though, in their understanding of what we can contribute to our salvation and forgiveness. Does Jesus pay the bill, or does He ask us to split it with Him?

The first place to start in understanding how Catholics and Protestants differ is in how they view the Bible. Catholicism teaches that Scripture and Tradition have equal authority while the Protestant church has held that the Bible is the only authoritative standard by which everything else is judged. This is the difference behind all the other differences.