In the fine print of church teaching (via the church’s lay apologists), being Protestant is inferior to being Roman Catholic. Jimmy Akin explains that Protestants are partial Christians:
the Catholic understanding is that Protestants are our brothers and sisters in Christ. So all Christians who profess faith in Christ and who are properly baptized are Christians and were put into a relationship with Jesus that Scripture describes in terms of being members of his Body. Different people have different degrees or forms of incorporation into His Body, though. And the goal is for everyone to be fully incorporated into Jesus, so we’re united with Him in the most ways possible. So that includes things like having the fullness of the Christian faith, understanding and accepting all of Jesus’s teachings. It also includes things like receiving all of the Sacraments that he would have us receive. Not just baptism, but the other Sacraments as well, and in the Catholic view there are seven sacraments.
It also includes being fully united with His Church, because Jesus said, “I will build my Church–” singular, not plural– “and the gates of Hell will not prevail against it.” So Jesus established a Church in the first century, and it’s continued down to the present day. And we also know that that Church is a visible Church, because he gave it leaders, like Saint Peter and the other Apostles, and the other ministers that they appointed to lead the Church in their absence, and so there has been a single visible communion of believers in Jesus that’s existed all the way from the first century to today.
The fullness of Rome has a lot to do with history — the apostles, the apostles’ successors, and the apostles Christ founded.
Not even Protestantism’s benefits can measure up to Rome’s antiquity:
[Protestants] still share many elements of grace, and have many wonderful aspects about them; they they honor Scripture, they may have a slight difference about, you know, what some of the books of the Bible should be, but they still honor God’s Word, they believe in Jesus, they believe in the Holy Trinity, they have a valid Sacrament of Baptism, and they have a lot of elements of grace and sanctification.
At the same time, we have to acknowledge that, you know, there are some differences between Protestants and Catholics, and from a Catholic perspective, those differences aren’t a good thing, … “What if someone knowingly refuses to accept something that Jesus willed us to have?”
If someone knew that the Catholic Church was founded by Jesus and that He wanted all of his followers to be united to it, and they said, “You know, I’m just not going to do that. I know Jesus wants me to do it, I know that he prayed for Christian unity on the night of the Last Supper, I know that’s a high on his priority list, but I’m just not going to do that,” well, then you’d have to question whether that person actually has a saving relationship with God, because he’s turning his back on something that’s fundamental and very important to Jesus, and therefore it looks, at least from outward appearances, like he’s cutting himself off from the means of grace that Jesus gave us. And so that person would be in spiritual jeopardy.
Is there salvation outside the Roman Catholic Church? The answer seems to be, yes, as long as either you don’t believe Rome is the church Jesus founded or you don’t know there’s no salvation outside the church. Knowledge (or ignorance) of the church is key as Akin claims:
You could have someone who, let’s say, was raised in a Protestant community, may have heard that Catholics believed Jesus founded the Catholic Church, but they don’t KNOW that; that hasn’t been proven to them, they haven’t seen sufficient evidence for that, and so through no fault of their own, they’ve never joined the Catholic Church–but they would if they knew that this was Jesus’s Church.
I know a lot of people who are in the Protestant community who would say, “Oh yeah, if I was convinced the Catholic Church was the one founded by Jesus, I would join it today.” Well, that person is not deliberately cutting himself off from from what Jesus would have him experience. He’s open to what Jesus would have him experience, and he’s already experiencing many elements of grace and sanctification. But he’s not deliberately refusing to do something he knows Jesus wants him to do. And so that person, even though they haven’t been fully incorporated into the Catholic Church, they’re still in a saving relationship with God. And so, if someone is not Catholic, through no fault of their own, but they’re otherwise responding to God’s grace, then they’ll be saved.
So the real question of salvation for Protestants is their knowledge of and degree of hostility to the Roman Catholic Church. A pious Protestant who hasn’t given much thought to Rome is apparently in a state of grace.
But if a person, whether they’re Catholic or not, refuses to do something of fundamental importance, like it could be not joining the Catholic Church, could be leaving, it could be any number of other grave things, like go out and commit murder or adultery; well, you’re deliberately defying the will of Christ in a fundamental matter there, and that will result in you being lost unless you repent. So everybody, both Protestant and Catholic, needs to be open to the grace that God wants us to have, and needs to be willing to respond to the call of Christ in all of these very fundamental matters.
The openness goes only one way though. Roman Catholics do not need to be open to the grace that is available in Protestant churches to be saved. For a Roman Catholic, salvation depends on the church. (Which is why a website can describe how to become Roman Catholic without ever mentioning Jesus Christ).