It is the Catholic faith without which one cannot be saved. Someone who has the Catholic faith and charity will at least implicitly desire full incorporation into the Church and that suffices for salvation. Bl. Pius IX’s comments (whatever authority they have) do not envisage salvation for those without faith. The question is whether it is possible to perform an act of faith after the age of reason without propositional knowledge of the Trinity and the Incarnation and this possibility is excluded by the Athanasian Creed and the Oath Against Modernism (definitive acts of the supreme magisterium).