Ignorance is a punishment from God. The withholding of grace, which leads to both spiritual blindness in this life and eternal damnation in the next life, is the result of sin. Humans are born guilty of Original Sin. The Church infallibly defined at the ecuмenical councils of Lyons and Florence, that the guilt of original sin suffices for damnation in hell. Through Baptism we receive the grace of the remission of original sin and washing away of its stain upon our souls.
“The souls of those who die in mortal sin or with original sin only, however, immediately descend to hell, to be punished moreover with disparate punishments. […] They will go into the everlasting fire prepared for the devil and his angels.” (Florence)
The Invincibly Ignorant are damned at least for the guilt of Original Sin. They are justly deprived of the only means of salvation, which is membership in the Holy Catholic Church (visibly, explicitly,....). They have neither innocence nor excuse in this matter. Their ignorance of the Divine Faith is a punishment for the original sin. It is the will of God, and it suffices for damnation.
Christ Lord said, "He who does not believe is damned already" (St. John 3) ‘for all have sinned’ (Romans 3), at least ‘in Adam’ (Romans 5). Knowledge of the only salvific Holy Catholic Church is a grace from God. We all are conceived damned for the original sin and will go to hell unless we die a Catholic in state of grace. Nobody is worthy of the Gospel or has any claim to receive it. Outside the Catholic Church, all humanity is cursed, to this day, with both physical and spiritual death, decay and corruption.
St. Augustine: “If you wish to be a Catholic, do not venture to believe, to say, or to teach that they whom the Lord has predestinated for Baptism can be snatched away from his predestination, or die before that has been accomplished in them which the Almighty has predestined.’