How can it be that the prot, baptist, lutheran, validly baptized and at one time (even for a moment) Catholic are excluded as a penitent?
They are excluded because they never had the faith. It can get confusing if you let it, and I am sorry for what I said re: Desmond's confusion, I did not mean it like it came out.
What is the difference between a prot who was validly baptized (and then rejects the Catholic Faith), and a heretic?
The heretic had the faith, the prot never had it. There are other differences, but in a nutshell, I think that covers it.
So, just to be clear, you do not hold that membership coincides with the indelible mark of Baptism?
Do you agree that it can be lost under some circuмstances?
If you clarify this, we may make progress, as we just did.
It coincides with the sacrament certainly, because one cannot be Catholic without baptism, but I do not see how baptism in and of itself makes one (an adult) a Catholic. You must have both, baptism and the Catholic faith. Even in the Creed, confessing one baptism for the remission of sins is only one of the things we Catholics must believe.
If we fall into heresy or apostasy or etc. then we commit mortal sin, if we die in that state then we go to hell, Catholic or not, it makes no difference - well, if there is a difference, we should expect that our suffering will be greater than non-Catholics.
But *for Catholics*, no matter what their sin, in an emergency it does not matter what offense we're guilty of, we can still be absolved in the sacrament of penance - which is something only Catholics can do.
So when the issue confuses, remember the fundamental teaching that no matter what our heresy, excom, mortal sin, etc., when in danger of death, we always can still go to confession, something non-Catholics cannot do. One reason that many heretics, schismatics, etc. do not take advantage of this, is likely because as they lived, so they shall die - in their sins.
If I am wrong, please tell me where I erred.