A good word from a young Luther
Indulgences are most pernicious because they induce complacency and thereby imperil salvation. Those person are damned who think that letters of indulgence make them certain of salvation. God works by contraries so that a man feels himself to be lost in the very moment when he is on the point of being saved. When God is about to justify a man, he damns him. Whom he would make alive he must first kill. God’s favor is so communicated in the form of wrath that it seems farthest when it is at hand. Man must first cry out that there is no health in him. He must be consumed with horror. This is the pain of purgatory. I do not know where it is located, but I do know that it can be experienced in this life. I know a man who has gone through such pains that had they lasted for one tenth of an hour he would have been reduced to ashes. In this disturbance salvation begins. When a man believes himself to be utterly lost, light breaks. Peace comes in the word of Christ through faith. He who does not have this is lost even though he be absolved a million times by the pope, and he who does have it may not wish to be released from purgatory, for true contrition seeks penalty. Christians should be encouraged to bear the cross. He who is baptized into Christ must be as a sheep for the slaughter. The merits of Christ are vastly more potent when they bring crosses than when they bring remissions.
There is some heavy stuff in that paragraph.
Seminary Ramblings 
Just curious, what did Luther himself believe about purgatory?
Luther, who spent the early part of his life as an Augustinian monk in the Roman Catholic Church, originally accepted the church’s teachings on purgatory, and even after starting to search the Scriptures for himself (where he began to reject many Roman Catholic teachings) it still took him a lot longer to renounce purgatory than it did many other doctrines. By 1530, and maybe earlier, Luther was clearly renouncing purgatory though.