Oh, please, Murph! The "heart" of the topic has been my point and true focus all along. The "Usual 'Catholic bad'"? There goes the persecution complex again.
No one has problems with someone coming to a deeper understanding of the tenets of the Christian faith but with the "development" of brand new doctrine not found in Scripture (the whole counsel of God) and definitely not with those that contradict Scripture.
To declare that Mary was conceived without sin and that she never sinned her entire life after she was born raises all kinds of problems with Divinely-inspired Scripture and was why Jesus didn't teach it, the Apostles didn't teach it, the early church didn't teach it (an optional "pious belief" by some, maybe, but not as doctrine) and it took the Roman Catholic church 18 centuries to declare it as "official" Catholic dogma and therefore, obligatory acceptance by all of Christendom. Protestants don't reject the IC because of hatred for Mary OR of the Catholic church. It's because the word of God is true and we can be confident that all Scripture is God-breathed and is useful for instruction, for conviction, for correction, and for training in righteousness, so that the man of God may be complete, fully equipped for every good work.
Newman trashed the Vincentian Canon (though he denied doing so) - The famous threefold test of Catholic orthodoxy expressed by St. Vincent of Lérins (400-50) in his two memoranda (Comonitoria): "Care must especially be had that that be held which was believed everywhere [ubique], always [semper], and by all [ab omnibus]." By this triple norm of diffusion, endurance, and universality, a Christian can distinguish religious truth from error. There is no unanimous consent of the fathers on many of the novel dogmas developed over the last few centuries by the RCC. The perversion of the doctrine of justification by faith bothers me way more than the IC, but that's a discussion for another day.
I reject the authority of the Roman Catholic church to dictate to every Christian what can and cannot be believed. God gave us His written word so that through it and the indwelling Holy Spirit, who leads us into all truth, we can have confidence in our faith. I respect your right to hold to your beliefs. Please do so for me.