This is not surprising, as Leo was a member of the wealthy Medici banking family, which dominated Florence. Leo's solution was to begin offering indulgences in exchange for donations to the Basilica's renovation.While these donations technically counted as pious works, Luther saw them as simple payment.
You can think of an indulgence as a 'get out of hell free' card.
The church had been in the practice of granting indulgences in exchange for good works and acts of piety for centuries, ever since Pope Urban II offered indulgences to Crusaders in 1095.
The dominance of the Roman Catholic Church remained unchallenged for nearly 500 years. He wasn't trying to destroy the Catholic Church or even start his own religion.
Then, in 1517, a German priest shook the Catholic Church to its very foundations. All Luther was trying to do was to stop the Church from engaging in some practices that he considered unchristian.
The church was supposed to be a spiritual sanctuary, not a marketplace.
So, Luther set about writing 95 complaints with the Church's greedy behavior. On October 3, 1517, Luther nailed his 95 Theses to the door of the Church of Wittenberg and sent copies to the higher authorities of the Catholic Church.
With all of these varieties living together in peace, it is easy to forget that about a thousand years ago, there was only one sort of Christianity allowed in Western Europe, and that was the Roman Catholic Church.
Following the Great East-West Schism of 1050, which divided the Orthodox East from the Catholic West, the Roman Catholic Church held unchallenged sway over the hearts and minds of Western Europe. Another country might elect its own pope, but by naming a pope, even those usurpers were still operating within the constraints of the Roman Catholic faith.
However, none can match Christianity for sheer numbers.
There are approximately 41,000 different denominations of Christianity.