What was one driving force behind the Reformation?

Joel Beeke explains in this video that the Protestant Reformation began as part of Martin Luther’s opposition towards the selling of indulgences to allegedly “release” souls from purgatory.

This abuse from the Roman Catholic Church contributed to one of the driving forces behind the Reformation — the issue of authority. Who is in charge of our lives? Is Scripture sufficient for everything or is the pope a second authority source that is of equal value to Scripture? If there is conflict between the two, which do you believe?

The fact that the pope seemingly had equal authority to Scripture forced the early Reformers to confront the issue of the authority of Scripture head-on.  

1 Thessalonians 2:13 (NKJV) - “For this reason we also thank God without ceasing, because when you received the word of God which you heard from us, you welcomed it not as the word of men, but as it is in truth, the word of God, which also effectively works in you who believe.”

In terms of the Protestant Reformation, there was not a single driving idea behind it. It actually began in a more apologetic polemical mode through Martin Luther's opposition to the selling of indulgences to release people's souls from purgatory. So it was the abuses of the Roman Catholic Church and the papacy that really began the movement and that then morphed into something much more significant so that the driving force behind the Reformation soon became the whole issue of authority. Who really is in charge of this world and in charge of our lives? Is it the Scriptures?

Are they sufficient for everything? Or is the Pope a second authority source that is of equal value to the scriptures Now Rome said the latter of course Once you say that however you've got a major problem Because if the Pope says to me today that Mary, for example, is sinless, and the Bible says that Mary trusted in God her Savior, which means she was a sinner, plain and simple, which do you believe? Well, if the Pope says it, Mary sinless. I must be misinterpreting, if I'm a devout Roman Catholic, Luke 1, where Mary confesses she's a sinner. So, bottom line, papal authority supersedes scriptural authority and you see that's where early on in the Reformation by 1520 already 95 theses posted in 1517 there were major objections against that so that's one major driving force, the authority of Scripture.