Now that we have established that Catholics can no longer hold to the opinion that explicit belief in the existence of a rewarder/punisher God can suffice for supernatural faith, let us expand on that.
What is supernatural faith?
If the authority upon which we base our assent is human and therefore fallible, we have human and fallible faith; if the authority is Divine, we have Divine and infallible faith.
There are two aspects to faith. 1) a supernatural object of faith (as per Vatican I) and 2) a supernatural formal motive of faith.
Let us now take some concrete act of faith, e.g. "I believe in the Most Holy Trinity." This mystery is the material or individual object upon which we are now exercising our faith, the formal object is its character as being a Divine truth, and this truth is clearly inevident as far as we are concerned; it in no way appeals to our intellect, on the contrary it rather repels it. And yet we assent to it by faith, consequently upon evidence which is extrinsic and not intrinsic to the truth we are accepting. But there can be no evidence commensurate with such a mystery save the Divine testimony itself, and this constitutes the motive for our assent to the mystery, and is, in scholastic language, the objectum formale quo of our assent.
So we have a supernatural object to which we assent based on extrinsic evidence, i.e. the authority of God revealing. That
a priori belief in the authority of God revealing constitutes what's referred to as the formal motive of faith.
But that formal motive must be based on an infallible and certain authority. We cannot have the certainty of faith regarding the object of faith without an authority that's known with the certainty of faith.
Protestants and others who refuse to accept the teaching authority of the Church base their adherence to these truths on "fallible and human" authority because their ultimate criterion for faith is their own private judgment rather than the authority of God.
Consequently, even when accepting truths such as the Holy Trinity, these are not known with the certainty of supernatural faith unless accepted on an authority that has the certainty of faith.
Consequently, there can be no supernatural faith outside the Catholic Church.
Consequently, only Catholics can be saved. I prescind here from any discussion regarding BoD for catechumens.