I think the answers lie in the fact that the Purgatorial Idea, though doctrinally a heresy, contains a spiritual truth when applied to the human situation. There is something in this false doctrine which reminds us of life. And there's the key.
There is very little, almost a non-existent Biblical case for Purgatory; and there is a most substantial Biblical case against it. Biblical soteriology and eschatology know nothing of it. Even the Catholic Encyclopedia admits: "In the final analysis the Catholic doctrine of purgatory is based on tradition not Sacred Scripture." So be it. The Biblical Christian must concur with The Anglican Thirty-Nine Articles, on this and like doctrines, that: "The Romish doctrine concerning Purgatory, Pardons, Worshipping and Adoration, as well of Images as of Relics, and also the Invocation of Saints, is a fond thing, vainly invented, and grounded upon no warranty of Scripture, but rather is repugnant to the Word of God." It is a negation of the Scripture itself to hear a Roman pontiff express the following reprieve: "An indulgence of three years is granted to the faithful who read the Books of the Bible for at least a quarter of an hour, with the reverence due to the Divine Word and as a spiritual reading. To the faithful who piously read at least some verses of the Gospel and in addition, while kissing the Gospel Book, devoutly recite one of the following invocations...an indulgence of 500 days is granted." The man who penned these words was ignorant of the gospel of Jesus Christ.
All these doctrines and practices are tied to a heterodox way of looking at the process of salvation. Human effort and merit are somehow made part of Christ's work on our behalf. Purgatory is a negation of the doctrine of grace; it is a monument to a theology of works. And that, after all, is the way fallen man likes it. But why, we keep asking, the aesthetic attraction?
Three literary examples readily come to mind when talking about Purgatory; they will help explain this theological error's imaginative power and appeal as an idea.
In Dante's Divine Comedy we find a tremendous treatment of Purgatory as an artistic, theological, and even political concept. It forms a hierarchical framework for medieval reality. It is a travelogue of the spiritual realms; a marvelous epic that takes one over the scenic road map of Catholic theology and Renaissance politics. It blends the classical with the Christian, giving guides for both worlds through Virgil and Beatrice. Its complexity is to art what Aquinas' Summa is to theology. Factual or false,the reader knows he is in the presence of artistic greatness--because he is in the presence of myth.
In C. S. Lewis's The Great Divorce, visitors from the Gray City take a day trip to Heaven. For those who stay, the visit is a kind of Purgatory; for those who return, heaven is just another part of Hell. Lewis's literary Purgatory was not intended as a doctrinal explanation of the afterlife. In his introduction he says of the tale: "I intended it to have a moral. But its transmortal conditions are solely an imaginative supposal." While he has his Virgil-esque mentor George MacDonald say: "And if ye come to tell of what ye have seen, make it plain that it was a dream. See ye make it very plain. Give no fool the pretext to think ye are claiming knowledge of what no mortal knows." Though Lewis was a believer in some form of purgatory, as allusions in Reflections On the Psalms indicate, he was not fighting for its inclusion as a tenet of mere Christianity. Although he used a purgatorial notion as the basis for his spiritual character studies, he recognized that reality was becoming more focused, more bifurcated, that in fact, a great divorce separated heaven from hell, and that this separation was widening.
The third piece which sheds some light on the sufferings of life is the non-purgatorial, puritanical Pilgrim's Progress. This primitive epic, like Dante and Lewis, sees life as a journey. It is a movement from spiritual death to spiritual life. We have in Christian's journey to the Celestial City, with all its pitfalls, snares, sloughs, dungeons, vain fairs, and adventures a picture of redeemed perseverance.
Now the Comedy is superior to Pilgrim's Progress as a myth and as a piece of art, just as a Cathedral is superior to a little Baptist chapel. And if we were to judge truth on the basis of architecture, as some people do, we might be all Romans, Orthodox, . . . or for that matter, Buddhists or Hindus--they've got wonderful pagodas. And the Mormons have neat temples too. But if we judge the art of Bunyan and Dante doctrinally, and effectually, then we have a different comparison. Bunyan in all his roughness is superior to Dante as the Bible is to Scholastic dialectic. The comparatively unlettered Bunyan towers over the urbane Dante; not by any worldly standard, but by every eternal standard. There will be few men in Heaven who have been led there by Dante's work, regardless of its obvious artistic superiority. There will be throngs in Heaven who will bless Bunyan the Evangelist, albeit the inferior artist, for leading them to the Narrow gate. Lewis, like a true Anglican--half Catholic, half Reformed--stands between them both.
Whatever truth there lies in Purgatory comes from its imaginative projection of the Christian life. For the Christian, life is a Bunyan-like sojourn, a Dante-esque cathartic experience, a Lewis-like movement from reprobation to salvation. It is suffering; it is cleansing. This is the fundamental Roman truth. Every piece of art is a little Purgatory: a place of spiritual battle, a time of playful suffering, a projection of human healing. It is in these artistic purgatories where we try to live out our metaphysical realities. It is one thing to use purgatory as an artistic platform; it is quite another thing to proclaim it as a doctrine.
The fundamental Roman error is the transference of this image, this imaginary doctrine, into the eternal realms. Purgatory is the here and now: Today is the day of damnation, today the day of cleansing, today the day of salvation. The doctrine negates the atonement, empties the gospel, encourages antinomianism, institutionalizes a system of works, and opens the door to work upon work of supererogation.
The failure to preach the true nature of the gospel results in the creation of untold spiritual miseries. Men fail to turn to God for their present salvation, since they know it can be purchased later; they fail to live a holy life now, since they know that their sins can be expiated by later efforts. They labor in spiritual solidarity with the dead through senseless devotions, masses, candles, prayers, pilgrimages, and rites, hoping to transfer merit to those who are either beyond hope, or who are presently in bliss. And they are unaware, that bankrupt in their own sins, they have no merit to transfer. They blaspheme the gospel with their indulgent works of supererogation; they attempt to buy the Holy Spirit's gift through pious effort. Purgatory produces a gospel of works extended into the afterlife. Not content to live a life of Semi-Pelagian heresy in this world, they extend it into the next. "The moment a coin in the coffer pings, out from purgatory a sinner springs." No wonder Luther penned his angry theses.
The value of purgatory is that of all creative fiction; it forms a framework for a Christian parable. It is not to be confused with Christian doctrine, wherein it forms the framework for damnation--as all heresy ultimately does. Purgatory must lead men away from God because it leads men away from the cross.
But do not let it be said that we are not imaginative men. Perhaps there is a purgatory. Perhaps there is this intermediate place "where the souls of those who die in the state of grace, but not free from all imperfection, make expiation for unforgiven venial sins or for the temporal punishment due to venial and mortal sins that have already been forgiven. . . " Perhaps being forgiven of our sins does not really mean that we are forgiven by Christ at all. Perhaps Christ's work on our behalf wasn't enough. Perhaps there are a hundred strange, absurd doctrines not found in the Bible. Perhaps all people who purposely sing off key will be ushered into heaven at the Second Coming. Perhaps the wearing of a piece of blessed brown cloth around your neck will entitle you to special treatment from the Almighty--you know, a kind of "This coupon entitles you to Eternal Life" special. Perhaps giving money, or lighting candles, or buying indulgences, or saying prayers, or making pilgrimages can work off a debt to God. Perhaps God accepts a line of credit: just make your easy monthly payments to the Bank of the Rock, and all will be well. Perhaps all this is true and our ancient Biblical faith is false. For if this is true, then clearly the Bible is in error. Call this new faith whatever you want, but don't call it Christianity. Call this ancient error what you will; but don't call it the Apostolic tradition.
As for those who do not follow the Purgatorial faith, we will continue to gather wisdom from the paradigm of the Divine Comedy and enjoy parabolic truth from The Great Divorce. For our lives are, indeed, "living sacrifices" and our journey is a Pilgrim's Progress. Dante for us is a poet; Lewis a teller of parables; Bunyan a preacher. In its fictive form, the Purgatorial idea -- like any piece of science fiction -- gives the artist the ability to clothe spiritual truth. As Lewis says: "Do not ask a vision in a dream more than a vision in a dream can give."
As for spiritual purgation, we will be content with the cleansing of the Cross.