Saint John of the Cross tells us that if we accept all the opportunities God gives us to purify ourselves on earth—the trials, even the penances He inspires in us—if we embrace them with gratitude (and not bitterness) and offer them to the Lord, we can be sure of going straight to Heaven! These offered trials replace Purgatory. God gives each soul sufficient grace to go directly to Heaven.
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The father of a nun who would later join her Carmelite community died as an atheist. Until the very end, he rejected the sacraments and the help of the Church. The Carmelite sister was truly distressed when she thought about her father's fate.
But she did not know that her deceased father had gone to visit Mariam* to ask her to pray for him, as he was suffering in purgatory. He explained to Mariam that, despite his categorical rejection of the sacraments until the end of his life, at the last moment, after clinical death, he saw a light. And thanks to that light, he repented and was saved from hell.
Mariam explained that one can never speculate about the final destiny of a soul.
* Saint Mary of Jesus Crucified (Mariam) Baouardy, Carmelite