There is a great article at California Catholic blog “Notes from A Cultural Madhouse” Read the whole thing, I have skipped some of the useful background and got to the meat here. My emphasis added.
“Subsists” is “Is” with a twist:
So, when Lumen Gentium says the Church of Christ subsists in the Catholic Church, it is saying that it exists only in the Catholic Church. In its very substance or essence, the Catholic Church is the Church of Christ.But in using subsists, the Council is saying something more.
As the Congregation for the Doctrine of the Faith’s June 29 “Responses to Some Questions Regarding Certain Aspects of the Doctrine of the Church” indicates, the Vatican Council’s use of subsists indicates the simpler is, but with this twist. Subsists, says “Responses,” “brings out more clearly” than is “the fact that there are ‘numerous elements of sanctification and truth’ which are found outside her [the Catholic Church’s] structure, but which ‘as gifts properly belonging to the Church of Christ, impel towards Catholic unity.’”
In using “subsists,” the Vatican Council attempted to get at the truth of the nature of the Church of Christ in a way that takes into account the very real salvific elements found in non-Catholic groups.
“Subsists,” however, does not stop at a simple recognition of the character of non-Catholic groups. It implies an ecumenism which finds its fulfillment It implies an ecumenism which finds its fulfillment only in conversion. For if elements of the Catholic Church exist outside her visible confines, they do not exist in the way that Christ willed for them to exist but as broken and scattered. As “Responses” said, only in the Catholic Church do we find that essential characteristic of the Church of Christ – unity – which gathers all the elements of truth, making them part of one substance. This being so, Catholics and non-Catholics alike are impelled to seek for themselves and each other that unity which, as Lumen Gentium says, “subsists in the Catholic Church, governed by the successor of Peter and the Bishops in communion with him.”
This work of conversion is not one-sided. For while it certainly implies, for non-Catholics, full entrance into the Catholic Church, it demands something of Catholics as well — the recognition of non-Catholic Christians as real, if separated, brethren and the zeal to bring our brethren home to the Church of Christ, which is, and subsists in, the Catholic Church.
The problem with some Catholics who reach out to our separated brothers and sisters is that they stop at the recognition of salvific elements outside of the Church. But we are called to more than that. We Catholics are challenged to invite our brothers and sisters home. That the we may be one. This requires a conversion on the part of our separated brothers & sisters. And it requires an active evangelization on our part. This isn’t relativism in action - it is a call to heal division through a conversion of separated Christians to unity with the Catholic Church. This is not “separate but equal,” and it is not about negotiating on matters of faith or morals. No, it is reaching out and teaching with humility.
