“My take on Dominus Iesus And on the Catechism is that Baptism (intention to baptize + water + trinitarian words) is the ordinary means of becoming a member of the Church. It is “ordinarily necessary” but not absolutely necessary.”
That’s loose theology, MD. Baptism, and Rome and the East understand the sacrament differently, at least along the margins, may very well signify a dedication of a person to God, but done outside The Church (and it is a point that there is absolutely no such thing as an “invisible” Church)and though the person may thereby become a Christian, that person is not ipso facto a member of The Church. As we know, they may be members of “ecclesial bodies” or “para-ecclesial groups” as we have sometimes called them, but not The Church. If they espouse heresy, they are not members of The Church but rather, as +John Chrysostomos calls them, “enemies of God”, perhaps lead there by the Evil One, but to the extent that they see The Church, to the extent that the teachings of The Church are known to them and nevertheless they reject them for heretical teachings like, for example, forms of universalism, they are cut off from The Church and the sacraments instituted by God for our Theosis.
The tough case, and we all know that tough cases make bad law, are those where by reason of delusion brought about by demonic influences, Christians reject The Church in a true and sincere belief that they are doing God’s will instead of the Evil One’s. I suppose we have to trust to God’s mercy there, as we do for ourselves and our own. My personal opinion is that the overwhelming majority of members of those eccesial groups are sincere, but resolutely refuse to undertake the sort of “self examination” in light of the teachings of The Church which might lead to that point where a choice must be made.
Easy for me to say, I suppose.
IN closing, I'd just like to say
DOE SNOT