I have realized by posting at CAF that the reason why the Vatican opposes gay marriage, abortion, human cloning, embryonic stem cell research, and euthanasia (the five non-negotiables) is not necessarily due to anything the Bible says, but rather what the Magisterium and Tradition say.
Same applies to theological concepts like the seven sacraments, purgatory, and the nature of Mary. It’s more based on the Magisterium and Tradition, as the biblical bases for these things are unclear and open to interpretation.
A quick example… Catholics interpret Matthew 12:32 “in this age or in the age to come” as indirectly referring to purgatory. But rather, it could just mean that the writer is emphasizing that forgiveness will not come in any point in time.
My question is, how can we authenticate the Magisterium?
How can we know that what the Vatican is teaching now is consistent with what the early church taught in Acts? It isn’t, right?
How do we know that today’s Holy Tradition is the same as that of the early church in Acts? It isn’t, right?
Some would say it’s due to apostolic succession. But putting aside church scandals, why does apostolic succession continue to be relevant, in the face of the Great Schism and Reformation?
How do we know that the teaching authority of the Church continues to be legitimate and not fraudulent? What makes the Catholic Church’s teachings more legitimate than that of a Protestant church? At least a Protestant church, although it may not have Apostolic Succession, is drawing solely from the Bible.