Tim Staples and the leading RCC apologetic site "Catholic Answers" gives the definitive answer to why Luther's heresy has persisted...
Several observations about this "answer"....
1. There's no mention of what Luther taught that was heresy.... What the RCC condemned was his teaching that Jesus is the Savior (not self, not now or ever, not in full or in part) - and he made it clear that he we speaking of narrow justiication (what in post Vatican II Catholicism is called "initial grace") and the RCC made it clear it understood how Luther meant it. THAT is what Luther said that the RCC was so horrified over that it split itself in the third largest split in Christian history. But (as is nearly always the case with Catholic Answers), it never says what the "heresy" is. IMO, the reason for this very obvious evasion is that the audience they are (in part) trying to reach would be horrified by the RCC's condemnation of that.
2. A huge point is made that sound theology is defined by having exactly SEVEN Sacraments - not 6 or 8 but 7. A denomination MUST define "Sacrament" as the post-Trent RCC does and MUST number such as exactly SEVEN. This is given as the keystone of theology. Not Christ. Not the Cross. Not the Resurrection. Not salvation. Not mercy. Having exactly SEVEN Sacraments - and defining the word "Sacrament" exactly as the RCC now does. Hum..... Tim goes on to say THIS is why the RCC is closer to the EOC than to Luther (although Lutherans don't dogmatically number them AT ALL, and the only one of the "seven" Luther personally indicated is not a "Sacrament" is marriage). So, the number SEVEN is the key, the singular most important thing in Christianity, the unifying point. Not Christ. Not the Cross. Not the Savior. Hum.... Sometimes when you read or listen to "Catholic Answers" - THE esteemed Catholic apologetics site - you learn far more than you'd expect.
3. Once again, we get the point perpetually made and very central to all Catholic apologetics, "The singular, individual RCC is in unity with just itself" point - and this PROVES it must be right and the singular denomination of God. This point that the RCC is in unity with ITSELF but no other is a constant at Catholic Answers, the "proof" pretty much for every point. Here Tim specifically rebukes the EOC because "it lacks the unity of the RCC" since there are minor (non - dogmatic) differences between the various national churches (no more than among the various rites in the RCC but never mind...). Because the Episcopal Church in the USA is ONLY in full unity with about 50 other denominations PROVES its wrong and the the RCC which is in full unity with NO OTHER, not ONE other - proves it HAS to be authentic, true, authoritative and correct. It has to be one of the most absurd, most laughable apologetics ever made but a constant at CA.
IMO, Luther's "heresy" that Jesus is the Savior has persisted because it's true and the Holy Spirit has empowered it. The RCC attempts to muddy that up with a lot of semi-Pelagianism and synergism, a lot of mixing of Law and Gospel, a lot of confusing and entangling, a lot of ignoring the Council of Orange, is perhaps the problem. I rejoice that the RCC has not lost the Gospel (even if it calls it "persisting heresy") just turned what should be the clearest of all teachings into its most confusing, and has displaced it with a doctrine it considers more important - that the denomination dogmatically states there are exactly SEVEN Sacraments, and the "evidence" of being correct not Scripture but that the denomination has zero unity, is in full unity with NONE, agreeing only with the one self sees in the mirror (even that only in those areas where self alone currently states that self should agree with self concerning).
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