HarleyD:
Ad for Mary, a special Grace from God is an accurate understanding for she was endowed with God’s Grace before the Coming of Christ. Stop and think about that. How is that you me and everyone else receives God’s Grace, it is thru the person of Christ and his life, death, and resurrection. Given Mary was endowed with the Grace of Christ before his paschal mystery, it is correct to say she received Grace in a special way due to God’s favor towards Her. I stand by that understanding as a Catholic. You do not. No need to debate it any more.
As for who is a member. All who are baptized in the Catholic Church are members. I would also state all who are Orthodox are members at a 99.9999999% confidence level. Those who are not, one would suggest that those who were validly baptized in the Holy Trinity, either explicitly or had a desire to do so “could also” be members of the Body. Thus, God himself would know who those are.
As for Joseph Smith, I will not say, but obviously, his understanding of the Trinity and Christ was fundamentally flawed [On this account, you Protestants are not], thus his situation “I would personally” say was more dangerous as to whether he was a member than say an orthodox protestant, who it is plausible could be and in many cases is part of the Catholic Church, even though they do not know it or recognize it.
Again, what is above is my personal reflection on the question. I assume it was an honest question and I hope yo take it as an honest attempt to answer.
And you have precisely argued what EVERY Reformer has ever argued. The problem is that you are ONLY applying this to Mary as if she was an exception. Reformers says that Mary was not an exception. God imparts this grace exactly the same way to everyone who is saved, by showing favor to us. And this favor isn't merited. It isn't because we are "liked" any more than anyone else or that we're swell people. It is simply because God chose to show us favor; just the way He did with Mary. Why is a mystery.