Pope Gregory XVI taught, "Finally some of these misguided people attempt to persuade themselves and others that men are not saved only in the Catholic religion, but that even heretics may attain eternal life.
A baptised Protestant child under the age of 7 most likely would be saved.
Sure, forlorn, this isn't the issue here at all. Every baptized child is Catholic. He ceases to be Catholic only when he becomes personally responsible for the errors of his sect, or when he denies the fundamental mysteries of the Catholic Faith, the Trinity and the Incarnation.
Let's be practical here - we're not talking about the hypothetical 7 or 10 year child, or even a 18 year old man or woman. We are talking about our Protestant co-workers, friends, colleagues, relatives, persons we know and generally talk to. Should we, by prayer and sacrifice above all, and secondly by evangelism and effort, work for their conversion to the Catholic Faith, as the only means to deliver them from hell. If you say yes, you agree with me. If no, then we disagree. The statement of Pope Gregory XVI is very clear. If we told it to a Protestant, he would understand it. If we are going to say Protestants can be anonymous Catholics, we are only one step away from pagans-can-be-saved-as-anonymous-Christians Rahner's theory.
If there's sufficient invincible ignorance, this means that they are truly Catholic and not Protestant.
Ok, Ladislaus. What about a 70 or 80 year old Protestant neighbor of ours, who has lived among Catholics all his or her life, and been told many times that they have to be Catholic to be saved. Will you say they are invincibly ignorant? My answer is invincible ignorance is not the issue. If they are culpably ignorant, they are formal heretics. If they are invincibly ignorant, they are material heretics. But being a material heretic is not the same as obtaining final perseverance. One of the effects of the Holy Eucharist, Ladislaus, is to prevent us from falling into future mortal sins, and to deliver us from daily venial faults. Trent says this. Similarly, all the Sacraments have their proper effects. A 70 or 80 year old Protestant has received none of them after Baptism. A Catholic Christian, who is striving to obtain final perseverance, has received several.
"But it is not enough to resolve never more to lose God; it is moreover necessary to adopt the means by which you may be preserved from the danger of losing him. The first means is, to avoid the occasions of sin; of this we have already spoken. The second is, to frequent the sacraments of penance and the Eucharist. In the house which is often swept there is no uncleanness. By the sacrament of penance the soul is purified; by it it obtains not only the remission of sins, but also help to resist temptations. The Communion is called the bread of heaven; because as the body cannot live without earthly food, so the soul cannot live without this celestial bread. Except you eat the flesh of the Son of man, and drink his blood, you shall not have life in you (John, vi, 54).
But on the other hand, to those who frequently eat this bread, is promised eternal life. If any man eat of this bread he shall live forever (John, vi, 52). Hence the Council of Trent calls the Communion a medicine which delivers us from venial, and preserves us from mortal sins (Sess. 13, cap. 2). " http://www.traditionalcatholicpriest.com/2017/06/17/final-perseverance-preparation-death-considerations-xxxi/
Moreover, final perseverance is to be sought primarily by prayer, St. Alphonsus and the Doctors tell us. But one should not depend so much on one's own prayers, as one should on the prayers of the Mother of God and the Saints. And this too Protestants don't do. And nobody who considers this reasonably will not see how precarious is the state of our Protestant friends and how desperately the Church is necessary.
Unfortunately, Pope Benedict XVI, in his discussion of EENS, says we no longer question that non-Catholics can be saved, but the real question, he says, is "why is the Church still necessary"? Sadly, this is where it ends up.
I'm not interested in getting into an interminable theoretical dispute. Are we interested in Protestantism remaining for another 500 years or are we going to pray and work for its extirpation in the next 50? We have the prophesies of the Age of Mary to come, when the Mother of God will triumph over all heresies, and Protestantism will disappear. We must believe and hope in that promise, and pray and work to obtain it. Part of that is seriousness about EENS, and the necessity for all to be Catholic. If just 1000000 Catholics would seriously resolve, by prayer and sacrifice primarily, to offer all their good works, Masses, Holy Communions, in union with the Sacred and Immaculate Heart, to obtain just one convert every year, anywhere in the world, and teach all Catholics and future converts they meet to do the same, there will be 10 million converts in 10 years, and it will keep increasing rapidly. This is our duty as Catholic Christians. If ecumenism had not confused many Catholics, Traditional Catholics included, we would all be doing just this daily.
What is the essence of false ecumenism? It is believing adult Protestants, who have tons of opportunities to convert, can be saved without being converted. St. Kolbe called it one of the most dangerous heresies of our time. This great Saint taught us every Knight of the Immaculata must work to counter false ecumenism and resist it by diametrically opposite action. St. Montfort says it is liberalism not to believe that devotion to Our Lady - because the grace of final perseverance is dispensed by Her hands, and primarily through Her prayers - is necessary for salvation. Needless to say, most adult Protestants have not invoked Our Lady's aid for salvation via the Hail Mary and similar prayers either. All these are part of what makes the conversion of our Protestant friends so urgent.
"§ 1. Necessary to all men to attain salvation.
40. The learned and pious Jesuit, Suarez, the erudite and devout Justus Lipsius, doctor of Louvain, and many others have proved invincibly, from the sentiments of the Fathers [among others, St. Augustine, St. Ephrem, deacon of Edessa, St. Cyril of Jerusalem, St. Germanus of Constantinople, St. John Damascene, St. Anselm, St. Bernard, St. Bernardine, St. Thomas and St. Bonaventure], that devotion to our Blessed Lady is necessary to salvation, and . . . that it is an infallible mark of reprobation to have no esteem and love for the holy Virgin; while on the other hand, it is an infallible mark of predestination to be entirely and truly devoted to Her." http://www.catholictradition.org/Mary/mary15d.htm
A final point, which Pope Benedict inadvertently touches on, is Catholics do not know how precious these things are - devotion to the Eucharist, devotion to Mary, etc - because now they are taught we can as well be saved without them. So, they are not esteemed.