Stubb,
Let's forget about specific people or theoretical examples; you are a master of getting discussions off track; let us as Andy insisted stick to fundamental Catholic principles. Once we settle on what is the criteria for being a Catholic as the Catholic Church has established (by citing official sources); then we can move on to applying those principles to specific cases.
Now, before deciding that this someone has left or is not a member of the Church, we must know what mortal sin he is guilty of committing to be the causation of his leaving the Church.
That is what you keep insisting is the only cause. We all agree that it can be one of the causes.
Obviously you will say the mortal sin of heresy is the cause, to which I will ask you to demonstrate where the catechism's all three things necessary (listed below) for that mortal sin are before deciding that this someone has left or is no longer a member of the Church.
Not so obvious; in fact this is what you keep insisting on is the ONLY cause; so you keep bringing up the "three conditions for a mortal sin" argument. By the way; we all agree on what are the three conditions for a mortal sin; if you remember correctly, I was the one arguing for the "three conditions" on the other thread. So lets shake hands on this, and get to the main point of contention. I will spell it out for you again: "Are material i.e. Innocent heretics members of the Church"?
This is where you tossed the catechism and run with Van Noort. But in doing that you ignore the elephant in the room Michael. All I am doing is putting a spotlight on the elephant so you cannot possibly miss it - except on purpose.
Reading this I am very tempted to think that you have nearly zero reading comprehension. I am the only one on this thread that has posted a quote from the Catechism!!
From Page 2, this is the second reply; from the Catechism of St Pius X:
https://www.ewtn.com/catholicism/library/catechism-of-st-pius-x-12869 Q. State distinctly what is necessary to be a member of the Church?
A. To be a member of the Church it is necessary to be baptized, to believe and profess the teaching of Jesus Christ, to participate in the same Sacraments, and to acknowledge the Pope and the other lawful pastors of the Church.
You see Stubb, the charge that I engaged in:"tossing the Catechism out and running with Van Noort"; when I did no such thing, can only come from a person like yourself, who regularly "tosses' out Church doctrine when it doesn't square with his own personal opinions. Secondly, why on earth would you even think that the two sources contradict each other? Thirdly, if they did contradict each other, why would I post them one right after the other?
The question/subject of this thread presupposes that the person is already a member of the Church, so deciding whether or not they meet the criteria, or ever were a member in the first place is unnecessary.
No, if there is no objective criteria for verifying who is a member of the Church, then we cannot know "who is a member in the first place"? How do you know that a person is a member? How do you establish this? What is the 'standard' that they Church uses?
The most normal and rational thing to do, is to consult an official source from the Church itself to see how she determines who is a member; then we can see who "fits" into this "standard"; is this so "wild and crazy" of an idea?