"You can be secure in Jesus"
Yes. Paul says nothing can keep us from the love of God and we can trust Jesus' promise. However, Scripture clearly tells us that WE can fall away from Christ. If we do not return, as the Prodigal son, we damn ourselves.
Btw, Purgatory is for the saved, and only God Himself can declare someone "fit" for heaven. Church teaching is that no one specific is in Hell. We don't know Hitler's faith in Christ before he died. (odds good he is not among the saved). God doesn't take away our gift. We give it up. Again, the prodigal son walked away on his own, he was not kicked out.
Regards
Where is the concept of purgatory found in the scriptures?
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