How could converting from a schismatic/heretical church to the Catholic Church possibly be a mortal sin? Even if a person in “convinced” that they are in the True Church of Christ while in protestantism, that would not mean that they are actually in it. At best it would have to be a form of invincible ignorance or something similar to believe that they are in accordance with Christ but in reality they are only imperfectly so at best.
Just because the protestants have an imperfect unity with the Catholic Church through baptism and some graces-all these graces flow from the Church. To visibly join the One, Holy, Catholic and Apostolic Church would be to be following God’s Word-That They All Become One. Not imperfectly one, perfectly One.
In other words, I propose that post-Vatican-II Catholics are caught in a bind. Vatican II will not allow you to maintain the traditional Augustinian position (or the more radical Cyprianic position, but fortunately you rejected that long ago) that separated communities have no claim on the baptism they transmit and that formation in them undoes the grace given by baptism. Vatican II clearly recognizes not simply that valid baptism is present in schismatic/heretical communities but that many other graces are present as well. And having said that, it is hard for you to mount a strong argument for the necessity of individual conversion on the part of non-Catholic Christians.
However, the groups talked about by St. Augustine and St. Cyprian are those like the Manicheans, Gnostics etc. whoever. At these early stages, many of the heretics were fallen away Catholics-after all, that is what a heretic is. Many practiced re-baptism etc. With protestantism, most of the protestants today were born into protestantism from generation to generation-thus they are not guilty of the sin of heresy. The original protestants that actually broke away from the Church did, however, commit the sin of heresy.
The Church still holds that anyone who leaves the Catholic Church for a heretical/schismatic/apostate group is committing grave sin. Those born into them (and thus not chosing to go) don’t commit this sin.
Why should non-Catholics join the Catholic Church? Short answer-because it is the True Church. Longer answer, it is Christ’s Church, built on St. Peter, with the fullness of Truth and the Sacraments (namely the Eucharist). Those who are not Catholics
may be saved-however-without recourse to the Sacraments it is not at all easy. It is not a cake-walk with recourse to the Sacraments!
Vatican II is definately not saying that all Christian (or even non-Christian) religions are equal to the Catholic Church. The Council merely states what is true-protestants are imperfectly united to Holy Mother Church by the efficacy of Baptism in the Trinitarian Form and thus are redeemed and salvation is possible. Salvation is possible to natives who’ve never even seen missionaries or have any idea what the Gospel is. That doesn’t mean that that sort of situation is good to be in. Who would not want the fullness of Truth? If presented with the fullness of Truth, to reject it is to reject Christ. The Church (and certainly not I) cannot know if a person is sincere or not about this. Only the individual knows if he sincerely, without reserve, believes that his church is the “true” Church or that in reality he just has too much pride to admit error and seek the True Church. No one knows, save our Redeemer and Judge, Jesus Christ.
