Answer:
The main idea was that believers could only be saved by their faith, not their deeds, and that they should repent to God instead of a priest. This idea was major because it meant that you could find salvation independent from the church and emphasized a more personal relationship with God.
Explanation:
In his thesis, Luther protested a lot of what the church was doing including confessions and indulgences. In his time, it was common for people to pay the priests to "forgive" or put in a good word about them when they talked to God or even reserve a place for them in Heaven. Having studied his Bible, Luther found that these practices weren't biblical and godly and made this known to the people who were being scammed.
