The Roman bishop Gregory the Great is believed to have played a key role in the acceptance and development of Purgatory during the Medieval period:
"Much, however, in Gregory fouls the sweetness of his instruction and his orthodoxy. As indicated, his allegory at time passes the bounds of outrageousness. Medieval interpretation suffered; formalization of his method closed Scripture to the laity. His credulous acceptance of stories of miracles performed by relics of the saints, sometimes of comical proportions and sometimes like the horror gimmicks of a slasher movie, helped create the massive burden of the medieval penitential system. Add to this his acceptance of the intercession of departed saints, his belief in the efficacy of masses for the dead, his anecdotal exposition of a state of purgatory, and his belief in the merits of pious works and a concoction alien to the biblical Gospel emerges. If for centuries Augustine of Hippo was read through the eyes of Gregory, it is no wonder that rediscoveries of the evangelical Augustine created such consternation in the sixteenth century."
The idea of indulgences stems forth from the dogma of Purgatory. Abuses within the Roman Catholic Church during the sixteenth century led up to the Protestant Reformation. According to the Encyclopedia Britannica:
"While reasserting the place of indulgences in the salvific process, the Council of Trent condemned “all base gain for securing indulgences” in 1563, and Pope Pius V abolished the sale of indulgences in 1567. The system and its underlying theology otherwise remained intact. Exactly 400 years later, in 1967, Pope Paul VI modified it by shifting the stress away from the satisfaction of punishment to the inducement of good works, greatly reducing the number of plenary indulgences and eliminating the numerical system associated for so long with partial indulgences."
The entire notion of doing good works in order to merit the grace of God runs contrary to Scripture. The sophisticated sacramental system of salvation that the Roman Catholic Church imposes on its followers is a perversion of the simple gospel of our Lord Jesus Christ. His shed blood is a foundational theme of the New Testament (Acts 20:28; 1 Corinthians 1:18-21; 6:20; Colossians 1:14; 1 Peter 1:18-19). With that being said, justification is a free gift of God (Romans 3:21-26; Ephesians 2:8-9). His grace is unmerited and not something that we deserve. Jesus Christ is our propitiation. We have peace with God by faith, not works (Romans 5:1-10).
The idea that we can make amends for our own sin or for the sins of other people in the sight of God undermines the sufficiency of Christ's atonement sacrifice. To suggest that we must pay the penalty for sin even after it has been pardoned by God diminishes the efficacy of His atonement. That is a terribly inadequate and inconsistent view of forgiveness.
Annually, thousands of Roman Catholics give money for Masses to be said for their deceased loved ones. Thus, we see how Purgatory in a sense makes God a respecter of persons (which contradicts what the Bible says regarding the character of God). Wealthier individuals can have more prayers and Masses said and so faster enter into heaven than those who are poorer. It wrongfully portrays God as judging on the basis of external factors rather than the heart. There is a purification process for believers on earth, which is through the blood of Jesus Christ (Hebrews 9:12-14).
How long does a person have to wait in Purgatory? How many prayers and Masses need to be said in order to get somebody out of Purgatory? The doctrine is a travesty of the gospel. Purgatory is contrary to everything that the Bible says about salvation and forgiveness. The tradition is based on creative speculation on what happens to believers during the intermediate state.