Under the eternal moral law, anyone who is in a state of formal heresy (knowingly and obstinately rejecting a definitive teaching of the Magisterium on a matter of faith or morals) is automatically excommunicated. Heresy excommunicates by the very nature of the offense, even apart from Canon law. But Canon law includes a provision excommunicating heretics:
Canon 751: “Heresy is the obstinate denial or obstinate doubt after the reception of baptism of some truth which is to be believed by divine and Catholic faith; apostasy is the total repudiation of the Christian faith; schism is the refusal of submission to the Supreme Pontiff or of communion with the members of the Church subject to him.”
Canon 1364 §1: “an apostate from the faith, a heretic, or a schismatic incurs a latae sententiae excommunication.”
The eternal moral law also requires that anyone who receive Holy Communion be in a state of grace. Therefore, anyone who is conscious of having committed an actual mortal sin, and who has not yet been to confession, generally cannot receive Holy Communion. (For a grave reason, and if such a person is repentant, he may say an act of perfect contrition, returning him to a state of grace, and then receive Communion.)
Canon law also has a provision prohibiting anyone who is unrepentant from manifest grave sin, regardless of whether the sin is actual mortal sin or merely an objective mortal sin, should not be offered Holy Communion.
Can. 915 “Those who have been excommunicated or interdicted after the imposition or declaration of the penalty and others obstinately persevering in manifest grave sin are not to be admitted to holy communion.”
Can. 916 “A person who is conscious of grave sin is not to celebrate Mass or receive the body of the Lord without previous sacramental confession unless there is a grave reason and there is no opportunity to confess; in this case the person is to remember the obligation to make an act of perfect contrition which includes the resolution of confessing as soon as possible.”
Now that we have reviewed some of the provisions of the moral law and of Canon law concerning which persons are prohibited from receiving Holy Communion, let’s consider a brief partial list of those Catholics who often receive Communion contrary to the teachings and rules of the Church, because they are either unrepentant from grave sin, or are guilty of heresy, or both.
In no particular order:
1. anyone using contraception, whether in marriage or outside of marriage, regardless of the purpose or circumstances;
2. anyone who believes that the use of contraception in marriage is moral, in some circumstances, or for some purposes;
3. anyone who believes that the use of contraception is moral outside of marriage;
4. anyone unrepentant from gravely immoral sexual acts of any kind (pre-marital sex, masturbation, homosexual acts, unnatural sexual acts within marriage, etc.)
5. anyone who believes that any of these various grave sexual sins are not sinful;
6. anyone who believes that homosexual acts are not gravely immoral, or that the homosexual orientation is not intrinsically disordered, or that same-sex marriage is a true type of marriage, or that same-sex marriage or civil unions should be legal
7. anyone making use of, or planning to make use of, IVF or other forms of artificial procreation;
8. anyone who believes that the use of IVF or artificial procreation is not always gravely immoral;
9. anyone who approves of the use of direct abortion in cases of rape, or incest, or birth defects, or to save the life of the mother;
10. anyone who is unrepentant from the grave sin of direct abortion;
11. anyone who is unrepentant from the grave sin of formal cooperation with any of the above mentioned (or other) grave sins;
12. anyone who believes the heresy that certain persons cannot possibly attain to eternal salvation, regardless of free will, because they have not been predestined;
13. anyone who rejects, in principle or in practice, the teaching authority of the Magisterium over the faithful, or the ability of the Magisterium to teach the truths of faith and morals infallibly.
14. teachers of any heresy.
15. persons who adhere to a heresy knowing it is contrary to dogma.
16. politicians and voters who directly vote to authorize or legalize or broaden the legalization of direct abortion.
17. schismatics, including anyone who rejects the authority of Pope Francis over doctrine and discipline, and anyone who rejects the authority of the body of Bishops over the same.
18. persons who are obstinately persevering in manifest grave sin.
19. anyone who encourages the faithful to hate, distrust, ridicule, disbelieve or disobey the Pope or the body of Bishops by speaking about the Pope and/or the Bishops with contempt, derision, malice, hatred, or denigration.
20. anyone who believes or teaches the heresy of Feeneyism, that only baptized Christians can be saved.
The above is only a partial list (updated 2/7/19). But is it clear that most Catholics who receive Communion do so contrary to either/both the eternal moral law or Canon law. In addition, many Catholic theologians and many Catholic bloggers also should not be receiving Communion, for multiple reasons listed above.
The foundation of the great apostasy has been laid.