What truth? It is Calvin's opinion. When he offers some scripture, he misses half the time, and his naked opinion is of no consequence to me.
The fact of the matter is that the whole idea of Purgatory is anathema to the whole of scripture and to any and all true systematic theology. Christ's work on the cross was finished when he so proclaimed it. If you want to suffer and die for your own sins, be my guest. But since the wages of sin is death, you will never be able to purge yourself from any of your sins. If Christ alone does not purge you of your sins, then your sins will go with you to the grave. And after that.... Judgment.