Note: This was written before my conversion to Orthodox Christianity and contains opinions I would no longer stand by.
For those Roman Catholics that believe that the doctrines revolving around purgatory are as old as the Church, think again:
It is a matter that may be inquired into, and either ascertained or left doubtful, whether some believers shall pass through a kind of purgatorial fire, and in proportion as they have loved with more or less devotion the goods that perish, be less or more quickly delivered from it. This cannot, however, be the case of any of those of whom it is said, that they
shall not inherit the kingdom of God, unless after suitable repentance their sins be forgiven them (Handbook on Faith, Hope, and Love, Chapter 69).
Augustine apparently did not pretend to know whether 1 Cor 3:11-15 was speaking of a literal Purgatory, as his own interpretation of the passage chapter 68 is that the passage pertains to experiencing loss of worldly attachments, and not purgatory.
Further, how can we ascertain whether there is a Purgatory? Obviously, Augustine felt that it should be argued from the Scripture. It is rather sad that those who defend the doctrine to this day, will lean upon the traditions of the Roman Catholic Church and not the authority that Augustine relied upon, the Scripture.