Can the faithful receive Holy Communion on repenting after committing a grave sin? At Matthew 26: 26-28, we read:


  While they were eating, Jesus took a loaf of bread, and after blessing it he broke it, gave it to the disciples, and said, “Take, eat; this is my body.”   Then he took a cup, and after giving thanks he gave it to them, saying, “Drink from it, all of you;   for this is my blood of the covenant, which is poured out for many for the forgiveness of sins.


That would imply that a member of the Church who is in a state of sin, but repents and receives the Body and Blood of Christ in Holy Communion should receive forgiveness for his/her  sins in the same way he/she gets absolution from sins in Confession. But, the Catholic Church has always been insisting that one should be in a state of Grace in order to receive Holy Communion in a worthy manner.

My question is: What has been the Catholic Church's answer to query on the above lines, raised by the faithful over the past few years?
"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.