My understanding is that only when a non-Catholic receives the revelation and comes to believe that only the Catholic Church has the complete Truth and believes that to be true but still refuses to enter in to it, is he in danger in the eyes of the CC. It is really based on the conviction of the person.
here’s what the CC teaches (2 links for context) Both Docs from Vat II
From Vat II and the document
Lumen Gentium November 21 1964
Excerpt for space
“
Basing itself upon Sacred Scripture and Tradition, it teaches that
the Church, now sojourning on earth as an exile,
is necessary for salvation. Christ, present to us in His Body, which is the Church, is the one Mediator and the unique way of salvation. In explicit terms He Himself affirmed the necessity of faith and baptism(124) and thereby affirmed also the necessity of the Church, for through baptism as through a door men enter the Church.
Whosoever, therefore, knowing that the Catholic Church was made necessary by Christ, would refuse to enter or to remain in it, could not be saved.”
"They are fully incorporated in the society of the Church who, possessing the Spirit of Christ accept her entire system and all the means of salvation given to her, and are united with her as part of her visible bodily structure and through her with Christ, who rules her through the Supreme Pontiff and the bishops. …
He is not saved, however, who, though part of the body of the Church, does not persevere in charity…"
Re:
“charity” Division from the Church is such an offense (sin) against charity.
And,
“whosoever” covers everyone not just Catholics
Also
Re: Separated brethren, from:
DECREE ON ECUMENISM
UNITATIS REDINTEGRATIO
“It is the urgent wish of this Holy Council that the measures undertaken by the sons of the Catholic Church should develop in conjunction with those of our
separated brethren so that no obstacle be put in the ways of divine Providence and no preconceived judgments impair the future inspirations of the Holy Spirit. The Council moreover professes its awareness that human powers and capacities cannot achieve this holy objective -
the reconciling of all Christians in the unity of the one and only Church of Christ. It is because of this that the Council rests all its hope on the prayer of Christ for the Church, on our Father’s love for us, and on the power of the Holy Spirit”…
Given in Rome at St. Peter’s, November 21, 1964
Re: separated brethren
Bottom line being
separated from the "
one and only Church of Christ" is against what Jesus prayed for… therefore, division needs to end for the sake of those separated