Conversion of the Holy Spirit

Hence they could not be saved who, knowing that the Catholic Church
was founded as necessary by God through Christ, would refuse either to
enter it or to remain in it.(Vatican II)

Another way of saying this would be:

"Whoever KNOWS that the Catholic Church was founded by God
through Christ but yet refuses to enter it could not be saved"

That leaves me and all Protestants off the hook then because we don't
KNOW that.

God working in us has told us that this claim by the RCC is not true so
we can be saved without entering the Catholic Church.

 

II Corinthians 4:7 indicates that the treasure that we have as Christians comes to us in the likeness of light that has shown into our hearts, that true Light [John 1:4] and glory which comes from the one Mediator, Jesus Christ. [I Timothy 2:5] The word 'have' as in 'But we have this treasure in earthen vessels . . . ' is in the present active tense, the word {ekomen} and suggests that at some point in time we received the Light of the world, [John 1:9] with the idea that actively on into the future we will have the triune God living in our hearts. The Spirit of God is not some kind of breeze that comes and goes, but is rather our Guide through this brief life, as our inner Advocate. [John 14:16] Our inward Attorney guides us checking us if we sin, giving us as sense of inner loss and conviction when we fall short of the glory of God. The ministry of the Holy Spirit is not to 'brake from camp and run from us, but to rather to take an eternal residence in our souls.

This is also reaffirmed in I John 3:9 where God says, 'Whosoever is born of God does not {poiei} practice sinning because His seed (the Holy Spirit) remains in him, so (the person) cannot make a practice of sinning.' This same Greek tense is in the present active indicative tense, where God says that after personal salvation takes place in the sinners life, that one cannot from that point on make a practice of sinning, because the Spirit of God is from that point on in control of that ones life.

True, a Christian may sin after he or she is in the faith, [I John 1:10 and I John 1:9] but then there is the loss of assurance of salvation, which hopefully will cause that one to confess that sin and return to the Lord to the original fellowship that was once enjoyed.

II Corinthians 4:7 also indicates that salvation is by grace through faith in Jesus plus nothing. ' . . . that the excellency of the power may be of God, and not of us.' Also, notice Ephesians 2:8-9. 'The gift of God . . . ' is the indwelling, permanent, Resident, the Spirit of God.

A person is saved and/or brought into the faith of Christ by receiving Christ. [John 1:12] 'But as many as receive Him, to those He gives the power {authority} to become the sons of God, even to those who believe on His Name.' Other than this, I know of no church formula that displaces this grounded and Biblical truth.