You very often hear that “you can’t be a Catholic and [fill in the blank]“. The [blank] is then filled in with whatever the person finds reprehensible, and what they consider to be grounds for ejecting somebody from the Church. The most common ones I hear are “you can’t be Catholic and be pro-choice”, or “you can’t be Catholic and support ‘gay marriage’”.
That can be a very tempting sentiment to express. Catholics must always adhere to the teaching of the Church — God forbid that I ever say or do anything against that teaching. There’s also something very distressing about people who proclaim themselves to be “good Catholics” or “devout Catholics”, yet take public positions or perform public acts that are inimical to that teaching. It misleads people, and it places souls at risk.
Now, I am no canon lawyer (I am a lawyer and some people want to shoot me out of a cannon, but that doesn’t count). But as I understand it, the general principle in Canon Law is that once you’re baptized a Catholic you’re always a Catholic, unless you formally defect — make a formal statement to your pastor that you are leaving the Church. That’s very rarely done. It’s actually very difficult to stop being a Catholic. Merely committing a sin is not enough.
That makes perfect sense. The Catholic Church isn’t a country club, where you lose your membership if you violate the rules or fail to pay your dues. It’s the Body of Christ, and we are incorporated into that Body by virtue of our Baptism — we are indelibly changed by the grace of that sacrament. It has become a question of who I am, and not just what I believe or do.
The key question then is not whether one ceases to be a Catholic, but to what extent a person is in communion with the Catholic Church, and thus with Christ Himself.
Full communion with the Church can be impaired by many things, such as heresy (rejection of a truth divinely revealed), schism (no longer attending Mass, but instead joining a religious group that is not in communion with the Holy See), etc. Failing to live a life in keeping with the teaching of the Church will also impair one’s communion (e.g., openly cohabiting with a non-spouse). Individual acts can also breach communion (like any mortal sin). In most of these cases, full communion is restored by sacramental Confession.
The USCCB described this once as “If a Catholic in his or her personal or professional life were knowingly and obstinately to reject the defined doctrines of the Church, or knowingly and obstinately to repudiate her definitive teaching on moral issues…he or she would seriously diminish his or her communion with the Church.”
Penalties like excommunication are imposed by the Canon Law in some particularly serious cases (e.g., heresy, schism, abortion, etc.). But they do not eject someone from the Catholic Church. Instead, they are public declarations that a person has breached communion with the Church in a significant way (e.g., those who participate in the purported “ordination” of women as priests). In these cases, full communion has to be restored, often by some other public act. The goal of these penalties is not to kick people out, but to call them to return.
So, for example, the poor deluded people who participate in mock “ordinations” of women have breached communion with the Church by their actions. Under Canon Law they have incurred an automatic excommunication. In no way are they Catholic priests. But they are still Catholics. Likewise with those who ordain bishops without the consent of the Holy See, or politicians who support intrinsically evil laws (such as those recognizing abortion rights, or re-defining marriage). They haven’t stopped being Catholic, but they have gravely wounded their communion with Christ and His Church.
Why does this technical distinction matter so much? Because it’s much easier to dismiss people as being beyond the pale, than to grieve for their sin and to work to reconcile with them and repair the damage. Anyone who has trouble in their family knows how tempting it is to wish that the difficult person were gone from the house, and how much harder it is for them to stay and work things out.
Reconciliation and healing are hard. Just ask the father of the Prodigal Son. Just ask Jesus.