Still waiting for an asnwer to this question:
If a 6 year-old schismatic in the state of grace is invincibly ignorant, by what means is grace forfeited (since full knowledge is necessary for the grave sin by which the grace is lost)?
Conversely, if the grace is not forfeited, how would such a one be damned?
As St. Thomas says, if he is incuplably ignorant he will receive the Gospel, if his ignorance is culpable he will be damned for his other sins.
It comes down to belief in Divine Providence. You actually believe that someone who is lives without mortal sin, sincerely seeking the truth would be denied it by God? If so, that's blasphemous.
Now please answer is belief in the Trinity and Incarnation obligatory pn all above the age of reason, by a necessity of means, for salvation?