I was drawing from the Catholic Encyclopedia, which refers to some gatherings in the 1400s. It was apparently an idea that developed over time.
I'm beginning to believe a lot of people who didn't have to struggle with becoming Catholic due to having been granted the grace to see the errors of the Protestant and Protestant derived religion they were in don't ever dig into the teaching of the Church. If so, that's probably the major reason why so many cradle Catholics fall for the propaganda, half-truths, and lies that lead them away from the Church and a real understanding of what Christ taught.
Check out post #27 in the thread about purgatory that's full of lies, misinterpretations of Scripture, and so on. That post has a good starting set of references and you can get several good books on the topic from Saint Benedict press, TAN, and others. It's worth spending time to study and understand because it's an amazing eye opener on just how merciful Christ really is. For all the bluster you might hear about any belief in purgatory being the same as doubting the sufficiency of the sacrifice Christ made, it's quite the opposite.
A real understanding of the Communion of the Saints and Purgatory leads you to a deeper understanding of how Christ paid for everything and is totally sufficient in every way, he also provided a complete and merciful way for us to be purified and enter heaven in the state we were created to exist in rather than just having our sin hidden a bit. You know, one guy wearing a batman cape to cover his sin, another less sinful guy just wearing a single white glove to hide his sin, and so on. No such BS, Christ has the perfect way to purify us through the fire to burn away the straw rather than a way to smuggle us into heaven in his diplomatic pouch.
That's not less belief in the sufficiency of Christ, it's a realization of just how His sacrifice is so perfect in that it makes Love, Grace, Mercy, and Justice, all work perfectly rather than ignoring the Justice intrinsic to God the Father and therefore, intrinsic to Christ. After all, Christ cannot be the perfect sacrifice unless He is perfectly Just as well as perfectly sinless.
JMHO
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