Question: It would seem that all infants who are not baptized with water before they die immediately go to Hell.
On the contrary: Although babies who have not been baptized with water may go to Hell, this does not mean God may not apply the grace of baptism to an infant through extraordinary means, such as by vicarious baptism of desire, as was espoused by Cajetan.
Objection 1: The Ecumenical Council of Florence declared: "The souls of those who die in actual mortal sin, or only in Original Sin, immediately descend into Hell," (Denz. 693) and since all infants contract original sin through their parents at the moment of conception, it follows that all infants who die without water baptism go to Hell.
Reply to Objection 1: Though infants who die in a state of original sin are deprived of the beatific vision and are also sentenced to eternity in Hell, this does not mean that God cannot, through extraordinary means, apply to an infant the grace of baptism before he dies, in order to remit his original sin, as the Catechism of the Catholic Church says:
As regards children who have died without Baptism, the Church can only entrust them to the mercy of God, as she does in her funeral rites for them. Indeed, the great mercy of God who desires that all men should be saved, and Jesus' tenderness toward children which caused him to say: "Let the children come to me, do not hinder them," allow us to hope that there is a way of salvation for children who have died without Baptism. All the more urgent is the Church's call not to prevent little children coming to Christ through the gift of holy Baptism. (1261)
Objection 2: Saint Augustine said:
It is this one Spirit who makes it possible for an infant to be regenerated ... when that infant is brought to baptism; and it is through this one Spirit that the infant so presented is reborn. For it is not written, "Unless a man be born again by the will of his parents" or "by the faith of those presenting him or ministering to him," but, "Unless a man be born again of water and the Holy Spirit." The water, therefore, manifesting exteriorly the sacrament of grace, and the Spirit effecting interiorly the benefit of grace, both regenerate in one Christ that man who was generated in Adam." (Letters 98:2)
Since the infant who dies before water baptism does not receive water, the infant cannot be born again.
Reply to Objection 2: Although one ordinarily must be baptized with water in order to receive the grace of regeneration, it is not absolutely necessary, as the Church recognizes that God may impart the grace of regeneration through the baptism of desire or the baptism of blood (Catechism of the Catholic Church, 1258). Furthermore, St. Augustine himself recognized the words of Jesus which read “unless a man be born again of water and the Holy Spirit” are not absolute, as he recognized exceptions to this statement, saying:
Those who, though they have not received the washing of regeneration, die for the confession of Christ — it avails them just as much for the forgiveness of their sins as if they had been washed in the sacred font of baptism. For he that said, "If anyone is not reborn of water and the Spirit, he will not enter the kingdom of heaven," made an exception for them in that other statement in which he says no less generally, Whoever confesses me before men, I too will confess him before my Father, who is in heaven. (The City of God, 13:7)
Objection 3: In the first quotation by St. Augustine above, he states that children are not born again by the will of their parents. Thus, an infant who dies without water baptism cannot be saved vicariously by the desire of the parents, as Cajetan posited.
Reply to Objection 3: Saint Augustine was attempting to safeguard the necessity of water baptism in ordinary circumstances. Given that it is conceded one must ordinarily receive water baptism in order to be saved, this doesn't mean there can't be extraordinary circumstances in which vicarious baptism of desire may be applicable for the salvation of an infant.
Objection 4: If an infant may be saved apart from water baptism, then abortion becomes good because it admits infants into the beatific vision.
Reply to Objection 4: On the contrary, we must never presume upon God's grace. We do not have a guarantee that God will apply the grace of baptism in an extraordinary way to an infant who dies without water baptism. For this reason, we may never believe that the evil of abortion is good. Furthermore, we are never permitted to use evil means in order to bring about a greater good.