Well, when you remove books from the Holy Bible in order to prove your point then you should have no problem with gays changing a few texts. There are certainly proofs of Purgatory. The Jews of Christ's time and Christ Himself believed in Purgatory. If Purgatory and its beliefs were incorrect I am sure Christ would have corrected this - at the very least the Holy Spriit would have.
The idea of Purgatory is simple. Only Christ can redeem Man. One's salvation is always through Christ. However, a person's attachment to sin, which makes up such a big part of their humanity must be cleansed. When you go to Heavean it will be without the attachment to sin. Purgatory is a state of being where the Person is cleansed of any attachment to sin.