Yes, Stubborn isn’t distinguishing between the various reasons for excommunication.  If a woman gets an abortion, she’s excommunicated but if she’s still practicing the Faith, she’s still a member.  If someone like Martin Luther is excommunicated for heresy AND THEN STOPS PRACTICING THE FAITH, he is obviously not a member anymore.  Faith is required for membership, as multiple popes have said.

That's your opinion. The Fathers did not teach any such thing - per Suarez.

What we know for sure is that Fr. Martin Luther died a Catholic priest: "Thou art a priest for ever, according to the order of Melchisedech."

The indelible mark of the Sacrament of Baptism on our soul is just as ineradicable as that of Holy Orders.

That's what I was taught.

Suarez didn’t say that heretics are still members.  

Yes, Stubborn isn’t distinguishing between the various reasons for excommunication.  If a woman gets an abortion, she’s excommunicated but if she’s still practicing the Faith, she’s still a member.  If someone like Martin Luther is excommunicated for heresy AND THEN STOPS PRACTICING THE FAITH, he is obviously not a member anymore.  Faith is required for membership, as multiple popes have said.

Spend 3 minutes and read the snips below to help you understand it's purpose what excommunication is. The snips are copied from the attached PDF which is the docuмent referenced in the 1917 Code of Canon Law.

Snip from the Forward...

Excommunication is the gravest of all canonical punishments ; it separates the delinquent from the communion of the faithful, and, practically speaking, deprives him of all the rights of membership in the Church of Christ. Were its dreadful character better known, no doubt the ends of ecclesiastical penal legislation would be more efficiently attained.

In the early ages the word excommunication was a generic term used to designate all ecclesiastical punishments and remedies. Consequently, the history of the censure of excommunication is very closely connected with that of ecclesiastical punishments in general; at times they are so closely allied that it is impossible to discriminate between them. Hence this work does not contain an exhaustive study of the history of excommunication. An attempt has been made, however, to gather together the salient points in its historical development.

Naturally, more attention has been given to the study of the effects of excommunication because of their practical importance. Excommunication is a medicinal punishment; its primary and immediate purpose is to bring the delinquent back to a sense of duty. The many and grave effects which follow upon the censure of excommunication are well calculated to accomplish this purpose.  The effects of excommunication are, as Cerato ( Censurae Vigentes , n. 37) remarks "totidem auxilia ac voces, quibus Pia Mater Ecclesia delinquentem et contumacem ad poenitentiam et ad salutem adducere contendit." (as many aids and voices, with which the Pious Mother Church strives to bring the delinquent and stubborn to repentance and salvation.) - Google Translate

Snip from the first chapter (re: Canon 2257).....

Etymologically, excommunication (Lat. ex, out of, away from ; communicatio, communication) signifies the separation of one from communication with others. In ecclesiastical law, it designates the act of excluding, or the state of being excluded from communication with the faithful, and is defined as a censure by which a person is excluded from the communion of the faithful with the effects which are enumerated in the canons and which cannot be separated.

Generically, therefore, excommunication is a censure, that is, a penalty by which a baptized person, delinquent and contumacious, is deprived of some spiritual goods, or goods annexed to spiritual things, until he ceases to be contumacious and is absolved. A censure is a penalty, that is, a privation of some good, inflicted by legitimate authority for the correction of the delinquent and punishment of the offense. It is a spiritual penalty, not only because it proceeds from a spiritual power and is inflicted for a spiritual purpose, but especially because it deprives one of spiritual goods, although secondarily it deprives one of temporal goods also. Moreover, it is a medicinal penalty, for its primary and immediate purpose is the emendation [correction] of the delinquent.

That's what I was taught.

Did Martin Luther die a member of the Church?

Baptism is a Sacrament which cleanses us from Original Sin, makes us Christians, children of God, and heirs of Heaven.

Baptism can be received only once because it places an indelible mark on the soul.

Spend 3 minutes and read the snips below to help you understand it's purpose what excommunication is. The snips are copied from the attached PDF which is the docuмent referenced in the 1917 Code of Canon Law.

Snip from the Forward...

Excommunication is the gravest of all canonical punishments ; it separates the delinquent from the communion of the faithful, and, practically speaking, deprives him of all the rights of membership in the Church of Christ. Were its dreadful character better known, no doubt the ends of ecclesiastical penal legislation would be more efficiently attained.

In the early ages the word excommunication was a generic term used to designate all ecclesiastical punishments and remedies. Consequently, the history of the censure of excommunication is very closely connected with that of ecclesiastical punishments in general; at times they are so closely allied that it is impossible to discriminate between them. Hence this work does not contain an exhaustive study of the history of excommunication. An attempt has been made, however, to gather together the salient points in its historical development.

Naturally, more attention has been given to the study of the effects of excommunication because of their practical importance. Excommunication is a medicinal punishment; its primary and immediate purpose is to bring the delinquent back to a sense of duty. The many and grave effects which follow upon the censure of excommunication are well calculated to accomplish this purpose.  The effects of excommunication are, as Cerato ( Censurae Vigentes , n. 37) remarks "totidem auxilia ac voces, quibus Pia Mater Ecclesia delinquentem et contumacem ad poenitentiam et ad salutem adducere contendit." (as many aids and voices, with which the Pious Mother Church strives to bring the delinquent and stubborn to repentance and salvation.) - Google Translate

Snip from the first chapter (re: Canon 2257).....

Etymologically, excommunication (Lat. ex, out of, away from ; communicatio, communication) signifies the separation of one from communication with others. In ecclesiastical law, it designates the act of excluding, or the state of being excluded from communication with the faithful, and is defined as a censure by which a person is excluded from the communion of the faithful with the effects which are enumerated in the canons and which cannot be separated.

Generically, therefore, excommunication is a censure, that is, a penalty by which a baptized person, delinquent and contumacious, is deprived of some spiritual goods, or goods annexed to spiritual things, until he ceases to be contumacious and is absolved. A censure is a penalty, that is, a privation of some good, inflicted by legitimate authority for the correction of the delinquent and punishment of the offense. It is a spiritual penalty, not only because it proceeds from a spiritual power and is inflicted for a spiritual purpose, but especially because it deprives one of spiritual goods, although secondarily it deprives one of temporal goods also. Moreover, it is a medicinal penalty, for its primary and immediate purpose is the emendation [correction] of the delinquent.

blah, blah, blah.  We're not talking about excommunication, but MAJOR HERESY, i.e. Martin Luther.

Stubborn, you keep "moving the goalposts";  you're dishonest.