This monumental act triggered the movement in world history known as the Reformation. While the historical date for the observance of Reformation is October 31st, most churches celebrate it on the last Sunday in October.
WHY WAS THE CHURCH IN NEED OF REFORM?
For centuries, the Roman Catholic Church had been overcome by false doctrines, superstition, ignorance, and corruption. Most people were illiterate and had little knowledge of the Bible; they relied on their Catholic Church for their religious teaching.
The monks, priests, bishops, and even the popes in Rome taught unbiblical doctrines like purgatory and salvation through good works. The average person in the pew sought to justify themselves by works, pilgrimages, and various kinds of religious duties and devotions.
The truth of the gospel -- the good news that God is loving and merciful, that He offers each and every one of us forgiveness and salvation not because of what we do, but because of what Christ has already done for us -- was not taught.
Today, Reformation Sunday is simply a day, as is every day to give glory to God for His sovereign work through Martin Luther and eventually many others as God caused the recovery of the gospel of salvation by grace through faith for Christ's sake.
Came down to earth to bear our sin.
Was it because of your own merit
That Jesus died your soul to win?
No, it was grace, and grace alone,
that brought Him from His heav'nly throne.