score:15
From the PoV of the Roman Catholic church, baptism is a sacrament for the living. (For that matter, so are all 7 Sacraments). Once the body dies one is subject to judgment, which in the case of individuals is particular judgment. Put simply, we have our whole life to come to Jesus, to open ourselves to salvation, and to accept God's sanctifying Grace. To be baptized is to be reborn in Christ and to wash away the stain of sin.
CCC 1213 Holy Baptism is the basis of the whole Christian life, the gateway to life in the Spirit (vitae spiritualis ianua), and the door which gives access to the other sacraments. Through Baptism we are freed from sin and reborn as sons of God; we become members of Christ, are incorporated into the Church and made sharers in her mission: "Baptism is the sacrament of regeneration through water in the word."
CCC 1214 ... to baptize (Greek baptizein) means to "plunge" or "immerse"; the "plunge" into the water symbolizes the catechumen's burial into Christ's death, from which he rises up by resurrection with him, as "a new creature."
CCC 1215 This sacrament is also called "the washing of regeneration and renewal by the Holy Spirit," for it signifies and actually brings about the birth of water and the Spirit without which no one "can enter the kingdom of God."
To baptize after the body has died and the soul has moved on to judgment would be a case of "closing the barn door after the horse left."
I. THE PARTICULAR JUDGMENT
CCC 1021 Death puts an end to human life as the time open to either accepting or rejecting the divine grace manifested in Christ. The New Testament speaks of judgment primarily in its aspect of the final encounter with Christ in his second coming, but also repeatedly affirms that each will be rewarded immediately after death in accordance with his works and faith. The parable of the poor man Lazarus and the words of Christ on the cross to the good thief, as well as other New Testament texts speak of a final destiny of the soul--a destiny which can be different for some and for others.
1022 Each man receives his eternal retribution in his immortal soul at the very moment of his death, in a particular judgment that refers his life to Christ: either entrance into the blessedness of heaven-through a purification or immediately, -- or immediate and everlasting damnation.At the evening of life, we shall be judged on our love. (~St. John of the Cross, Dichos 64.)
Put another way, if you don't have a relationship with Christ while living, there is no basis for a favorable judgment. (I suppose that hope is always an option, part of why the Catholics pray for the dead ... but that's getting off topic). In Matthew (7:21 – 23) Jesus teaches that some will come to judgment and be told "Depart from me, I never knew you." If we don't have a relationship with Him before death, this passage points to us being out of luck at judgment. The foundation of that relationship is the gateway sacrament: Baptism.
Caveat: the above isn't the only way to parse Matthew 7's larger point, but I've heard this referred to on multiple occasions among Catholics, both lay and clergy, when emphasizing how important it is to have a relationship with Christ.
For a better understanding of Catholic views on Baptism, articles 1213-1228 in the Catechism are helpful.
Upvote:2
My answer is similar to KorvinStarmast's, but I use a more authoritative source:
One is judged immediately after death, as Benedict XII defined in his constitution Benedictus Deus:
By this Constitution which is to remain in force for ever, we, with apostolic authority, define the following: According to the general disposition of God, the souls of all the saints who departed from this world before the passion of our Lord Jesus Christ and also of the holy apostles, martyrs, confessors, virgins and other faithful who died after receiving the holy baptism of Christ—provided they were not in need of any purification when they died, or will not be in need of any when they die in the future, or else, if they then needed or will need some purification, after they have been purified after death—and again the souls of children who have been reborn by the same baptism of Christ or will be when baptism is conferred on them, if they die before attaining the use of free will: all these souls, immediately (mox) after death and, in the case of those in need of purification, after the purification mentioned above, since the ascension of our Lord and Saviour Jesus Christ into heaven, already before they take up their bodies again and before the general judgment, have been, are and will be with Christ in heaven, in the heavenly kingdom and paradise, joined to the company of the holy angels. Since the passion and death of the Lord Jesus Christ, these souls have seen and see the divine essence with an intuitive vision and even face to face, without the mediation of any creature by way of object of vision; rather the divine essence immediately manifests itself to them, plainly, clearly and openly, and in this vision they enjoy the divine essence. Moreover, by this vision and enjoyment the souls of those who have already died are truly blessed and have eternal life and rest. Also the souls of those who will die in the future will see the same divine essence and will enjoy it before the general judgment.
Thus, one must be baptized—either by water, desire, or blood—before one's soul separates from the body if he is to enter purgatory or heaven.
Upvote:4
I would like to add to KorvinStarmast's excellent answer that all of the sacraments have three essential components common to all seven of them:
A sign: some kind of physical sign that is performed. (This sign can then be resolved in most of the sacraments into the “matter”—generally either whatever is transformed by the sacrament, or the physical gesture used—and the “form”—generally, the words that are spoken to effect the transformation or accompany the physical gesture. Some of the sacraments do not fit this model easily, but for Baptism the matter is the washing with water, and the form is the Trinitarian formula.)
A minister: the person who performs the gesture and pronounces the necessary words (if that is necessary).
A subject: the person or thing that is transformed (like the bread and wine for the Eucharist, or the person receiving the sacrament in all the other cases).
(For instance, if you look at the Catechism of the Catholic Church in its section on the Sacraments, 1210-1666, you will see subheadings under each sacrament that say, “How is the sacrament celebrated?” “Who can receive this sacrament?” and “Who can administer this sacrament?”)
In the case of Baptism, the subject must be an unbaptized, living human being. (CCC 1246; it must be an unbaptized person, because a baptized person cannot be re-baptized; he can never lose the indelible mark or “character” that he receives at Baptism—see CCC 1272.)
As far as attempting to baptize a dead person: it is important to keep in mind that such an act would be attempting to baptize, not a human person, but a human corpse—which is actually not a human person, just the remains of one. (The human person in question is now a disembodied soul awaiting the general resurrection—see CCC 989.) Hence, it would not have any effect.