Can the faithful receive Holy Communion on repenting after committing a grave sin?

The question presupposes a person may be unworthy to take communion. And that taking communion when you are in an unworthy state has severe consequences.

I challenge that assumption. And I justify my answering the better question because Jesus often did not address the actual question, but addressed the issue at the heart of the question.

The word used was worthily, not worthy. Worthily is an adverb, not an adjective. The issue is not that the person is unworthy (that would be the adjective). The act of taking communion is what can be done unworthily. If you think that you have worthied up, confessed you sin so you are now not in danger of being unworthy, you have missed the point. And you are in danger of taking it unworthily. Let me explain:

John 13:12 Jesus began the Last Supper by washing the feet of the disciples. He said "If I then, your Lord and Master, have washed your feet; ye also ought to wash one another's feet. For I have given you an example, that ye should do as I have done to you."

Jesus was not talking about washing feet. Washing feet was only an example. The point is that what Jesus has done for us, we should do for one another. What has Jesus done for you? What did he do later that evening?

Jesus broke the bread and said, "This is my body, broken for you: this do in remembrance of me." If Jesus had said after he washed their feet, "This do in remembrance of me" would he be referring to allowing people to wash you feet in remembrance of him? Of course not. He would be talking about washing the feet of others in remembrance of him. When Jesus said do this, the this he was referring to was offering your body, broken for others.

Taking communion unworthily is receiving the broken body of Christ, and not reciprocating by offering your body, broken for others, and willing drinking the cup - even the cup that Jesus was reluctant to partake.

The 1 Corinthians 11:28-31 passage can be confusing, because of all the clutter. It wanders off on a few tangents, then come back on track and you can get lost in the redirections. Let me remove the clutter, then you will see how it makes sense: 1 Cor 11:28 But let a man examine himself, 29 not judging the Lord's body. 31 For if we would judge ourselves, we should not be judged.

In verse 29, the word discern is used, but it is the same Greek word translated judged in verse 31.

So what is the meaning of the unworthily part? When we gather together, if we judge one another instead of judging ourselves, we are in danger of having our judgments measure out to us again.

Matthew 7:1 Judge not that ye be not judged, For with what judgment ye judge, ye shall be judged, and with what measure ye mete, it shall be measured to you again.

When we do to others what Jesus has done for us, we show forth his death until he comes. To do this properly, we need to remember how he did it. He did not consider himself the victim of a robbery, he did not play the role of the martyr. He laid down his life willingly. Be like minded. And that is what he meant by doing "this" in remembrance of him.

And how did he do it? 1 Cor 11:23 That the Lord Jesus the SAME NIGHT in which he was betrayed took bread: And when he had given thanks, he brake it, and said, Take, eat: this is my body, which is broken for you: this do in remembrance of me.

How long is the proper period for holding a grudge? Jesus, on the SAME NIGHT. He is not asking to do what he has not done.

When we take communion worthily, we demonstrate the Lord’s death by passing on to others what we ourselves have received, remembering to deliver to others in the same spirit which it was given unto us.

"my blood of the covenant, which is poured forth for many for the forgiveness of sins" refers to the purpose of the giving of Christ's blood. It does not refer to the effects of recieving it in Communion.

This is the very simple answer.

However, we do believe that the body and blood of Christ give us spiritual life. As Christ lives by the Father, so we will live because of Christ, and will be raised, like Him, on the last day. Theses are the promises of Christ on the Eucharist.

St. Paul teaches that we must have a clean conscience before Holy Communion:

1 Corinthians 10:16-22. . . 11:25-29

The cup of blessing, which we bless, is it not the communion of the blood of Christ? The bread, which we break, is it not the communion of the body of Christ? . . . Are not those who eat the sacrifices partakers of the altar?* . . . But you cannot drink the cup of the Lord and the cup of demons; you cannot partake of the table of the Lord** and the table of demons. Or do we provoke the Lord? Are we stronger than He? . . . [about misconduct at the Lord's Supper] . . .

For I recieved from the Lord what I also passed on to you: that the Lord Jesus, on the night he was betrayed, took bread, and having given thanks [eucharistēsas] He broke it and said, This is My body, which is [given] for you; do this in commemoration of Me. In the same way, having supped, [took] the cup, saying, This cup is the new covenant in My blood; [and] as often you might drink it, do it in commemoration of Me. For as often as you eat this bread and drink this cup, you proclaim the death of the Lord until He comes. Therefore WHOEVER EATS THE BREAD OR DRINKS OF THE CUP OF THE LORD UNWORTHILY WILL BE GUILTY OF THE BODY AND BLOOD OF THE LORD. Therefore let a man examine himself, and then let him eat of the bread and drink of the cup. For he who eats and drinks not recognizing [for what it is] the body/flesh [of the Lord] eats and drinks DAMNATION unto himself: for which reason many of you are weak and sick, and many of you fallen asleep.

* Hebrews 13:10.

** table of the Lord refers to the altar of sacrifice referred to in the Old Testament:

Malachi 1:7

You offer polluted bread upon My altar. And you say, Wherein have we polluted Thee: in that you say the table of the Lord is contemptable.

The Catechism of the Catholic Church teaches the following:^§

To respond to this invitation we must prepare ourselves for so great and so holy a moment. St. Paul urges us to examine our conscience: "Whoever, therefore, eats the bread or drinks the cup of the Lord in an unworthy manner will be guilty of profaning the body and blood of the Lord. Let a man examine himself, and so eat of the bread and drink of the cup. For any one who eats and drinks without discerning the body eats and drinks judgment upon himself."²¹⁶ Anyone conscious of a grave sin must receive the sacrament of Reconciliation before coming to Communion.

²¹⁶ 1 Cor 11:27-29.

^§ CCC 1385 | See also Council of Trent, Session 13, Concerning the Most Holy Sacrament of the Eucharist, cap. VII.