Scripture (which is uniquely inspired) must be interpreted. Either everyone’s interpretation is equally valid (or invalid), or Jesus founded a church whose leaders are able to offer an interpretation that trumps mine.
If God does not protect His Church from error (some way, somehow, under some conditions or other), then there is no reason whatsoever to suppose that He protects anyone from error. And if He doesn’t protect anyone from error, then there is no reason to suppose that Christianity (of any stripe) is true. Because if the Church isn’t infallible in some sense, there is no basis for believing that God has spoken in the Bible. It is reduced to just one book among many for which claims of divine authorship are made, and there’s no good reason to accept the claims about the Bible if the Church cannot be trusted. The rationality of Christianity stands or falls with a Church that God protects from teaching error with regard to faith and morals.