No worries. Our goal should only be to increase in merit and advance in holiness each and every day and hour of our lives. If all the world is against us, because we preach the love of God and His Church, the necessity of the Catholic Faith and the Sacraments, of Penance and of good works, of devotion to Our Lady and seeking Her intercession and mediation, what is that to us? If God be for us, who can be against us? I believe all Traditional Catholics working for restoration will soon see themselves as being on the same side. I certainly don't see anyone, even those who disagreed with me on this thread, as being an "enemy" to be "defeated", but rather a brother or sister or friend to exhort or receive advice from. But thanks for the warning, if it turns out as you say, I'll be forewarned.
My opinion is focusing on final perseverance is safer and surer, or at least more likely to be accepted by our fellow Traditional Catholics, than some of the other arguments and demonstrations made use of by Fr. Damen and Fr. Mueller. Fr. Mueller is quite clear at the same time that we cannot pass final judgment on any other soul, but we can and must pray and work for their conversion and salvation. If a soul receives the grace of a deathbed conversion, he or she would receive justification and perseverance together.
Q. Are all those who are out of the Church equally guilty and damnable before God?
A. No; some are more guilty than others.
Q. Who are least guilty and damnable?
A. Those who, without any fault of theirs, do not know Jesus Christ or His doctrine at all.
Q. Who are most guilty and damnable?
A. Those who know the Catholic Church to be the only true Church, but do not embrace her faith, as also those who could know her if they would candidly search, but who, through indifference and other culpable motives, neglect to do so.
Q. What are we to think of the salvation of those who are out of the pale of the Church without any fault of theirs, and who never had any opportunity of knowing better?
A. Their inculpable ignorance will not save them; but if they fear God and live up to their conscience, God, in His infinite mercy, will furnish them with the necessary means of salvation, even so as to send, if needed, an angel to instruct them in the Catholic faith, rather than let them perish through inculpable ignorance.
Q. Is it then right for us to say that one who was not received into the Church before his death, is damned?
Q. Why not?
A. Because we cannot know for certain what takes place between God and the soul at the awful moment of death.
Q. What do you mean by this?
A. I mean that God, in His infinite mercy, may enlighten, at the hour of death, one who is not yet a Catholic, so that he may see the truth of the Catholic faith, be truly sorry for his sins, and sincerely desire to die a good Catholic.
Q. What do we say of those who receive such an extraordinary grace, and die in this manner?
A. We say of them that they die united, at least, to the soul of the Catholic Church, and are saved.
Q. What, then, awaits all those who are out of the Catholic Church, and die without having received such an extraordinary grace at the hour of death?
A. Eternal damnation.