The Catholic Church teaches that martyrdom can be a substitute for baptism of water because by it the person is actually conformed to the Passion of Christ from which springs the efficacy of the Sacrament of Baptism. Hence there is no need to fear for the salvation of catechumens whom the executioner’s sword cuts down before they can be baptized. But, what if, instead of the executioner’s sword, it is sickness or accident that prevents a person from receiving the sacramental rite? Will this person deprived of the grace of martyrdom and Baptism “in re” still be saved? Our Lord Jesus Christ, followed by the Fathers, Popes and Councils of the Church, has taught us that Baptism is absolutely essential in order to win eternal life: “He that believeth and is baptized shall be saved...(Mark 16:16 ;John 3:5) . In another case, we know in the Holy Scripture that the centurion Cornelius and his household received the Holy Ghost before they were baptized. (Acts 10:44-48)
It is the teaching of the Catholic Church that when the baptism of water becomes a physical or moral impossibility, eternal life may be obtained by the baptism of blood or by the baptism of desire (voto).
Thesis: Besides the baptism of blood, there is another kind of baptism that can substitute for baptism of water, which is called ‘baptismus flaminis’, a baptism
“in voto”. (proxima fidei)
NOTION & PROOFS OF ITS EXISTENCE:
The baptism of desire (baptismus flaminis sive Spiritus Sancti) is a perfect contrition of heart, and every act of perfect charity or pure love of God which contains, at least implicitly, a desire (votum) of baptism. The Latin word flamen is used because Flamen is a name for the Holy Ghost, Whose special office it is to move the heart to love God and to conceive penitence for sin. The "baptism of the Holy Ghost" is a term employed in the third century by the anonymous author of the book "De Rebaptismate". St. Thomas also calls it “baptism of the Holy Ghost" because it is the Holy Ghost giving the Light of Faith and burning love of Charity in the soul.
The existence and the efficacy of the baptism of desire to supply the place of the baptism of water, as to its principal effect, are proved from: (A). the Words of Christ, viz. Holy Scripture; (B) Church’s Fathers; (C) the Magisterium of the Church (D) Reason.
A. From Holy Scripture.
1) After Christ had declared the necessity of baptism (John, iii), He promised justifying grace or an infusion of sanctifying grace for acts of charity or perfect contrition (John, 14:21-23): "He that loveth Me, shall be loved of my Father: and I will love him and will manifest myself to him." And again: "If any one love me, he will keep my word, and my Father will love him, and we will come to him, and will make our abode with him." And St. Luke 7:47: “ Many sins are forgiven her because she hath loved much.” Since these texts declare that justifying grace is bestowed on account of acts of perfect charity or contrition, it is evident that these acts supply the place of baptism as to its principal effect, the remission of sins. Directing principle: mortal sin and sanctifying grace are incompatible. (St. Thomas, III, q.86, a.3)
See also the following texts, which convey the same idea. Prov.8: 17; 10:12; Luke 10:27-28; 1 Peter 4:8; 1 John 3:14 sq.; 14:7
A DEDUCTION: From the texts we have just seen above, we can deduce that no one sincerely loves God or Christ unless he “keeps,” in so far as he can, “the word of Christ”(Jn.14: 23); but Christ has taught that baptism of water is necessary for salvation; “...unless a man be born again of water and the Holy Ghost, he cannot enter into the kingdom of God.”(Jn.3: 5) Therefore, he who knowingly and willingly neglects Baptism, does not love God. But he who sincerely wills to observe all the teachings of Christ, in so far as he can, desires to be baptized and therefore has already perfect charity, even if here and now he is impeded from the reception of the baptism “in re”, and consequently he is already justified: “He shall be loved of my Father, and my Father will love him.”
2) This doctrine is also confirmed by the example of Cornelius (Acts 10:2, 44-48) who, seeking God with his whole heart, had received the Holy Ghost before he was baptized.
B) The Fathers of the Church.
1) Clement of Alexandria (150-215 a.d.) in his book Stromates, 4,4, and St. Cyprian, in his pastoral letter to Fortunatus (Ad Fortunatum) on the duties of the Christians in times of persecution, taught implicitly doctrine of Baptism of desire.
2) St. Ambrose- (340-397 A.d.) The first text that explicitly expresses the notion of baptism of desire is the famous funeral homily preached by this saint over the Emperor Valentinian II, a catechumen. The young emperor was assassinated by order of Arbogast while St. Ambrose had set out at the emperor’s request to come and baptize him and help him evade the ambush of his enemies. St. Ambrose was deeply moved by his untimely death, as were the faithful. What they could hope for his eternal salvation? Here is a quotation of the saint’s funeral oration in which he explicitly sets forth the doctrine of the baptism of desire.
“But I hear that you grieve because he did not receive the sacrament of baptism. Tell me: What else is in your power other than the desire, the request? But he even had this desire for a long time, that, when he should come into Italy, he would be initiated, and recently he signified a desire to be baptized by me, and for this reason above all others he thought that I ought to be summoned. Has he not, then, the grace which he desired; has he not the grace which he requested? And because he asked, he received, and therefore is it said: “By whatsoever death the just man shall be overtaken, his soul shall be at rest”(Wisd. 4:7). 
3) St. Augustine (354-430 a.d) declared : “ I find that not only suffering for the sake of Christ can replace that which is lacking in Baptism, but also faith and conversion of the heart (fidem conversionemque cordis), if perhaps the shortness of the time does not permit the celebration of the mystery of baptism” (IV, De Bapt., xxii)
Early Scholasticism: St. Bernard (Ep. 77 c.2 n.6-9), Hugo of St. victor (De sacr. II 6,7).
C). Church’s Magisterium:
1). Council of Trent, session 6, chp.4, on the Decree of Justification, explicitly teaches that justification from original sin cannot be obtained “except through the laver of regeneration (i.e. baptism of water) or a desire for it” (voto) dz. 796; also session 7, cn.4 on the sacraments ‘in general’, dz. 847, and session 14, chp.3, declares that perfect contrition reconciles man to God, but not without the desire of the sacrament, which is included in it, dz. 798.
2). a) St. Pius V condemned the proposition of Bajus, dz. 1033 & 1031: “Perfect and sincere charity, which is from a “pure heart and good conscience and a faith not feigned”, can be in catechumens as well as in penitents without the remission of sins.” Hence, the catechumens who possess this “perfect and sincere charity” are already justified even though they have not yet received the sacrament of Baptism, since in this case, they have already obtained pardon for their sins.
b) Pope Innocent II, on the authority of the holy Fathers Augustine and Ambrose, explicitly asserted that the priest who died without the valid sacrament of Baptism “has attained the joy of the heavenly fatherland”, “because he persevered in the faith of holy mother the Church and in the confession of the name of Christ”. Dz. 388.
St. Thomas, in his Summa Theologica, III, q. 68, a.2, says, “the sacrament of Baptism may be wanting to anyone in reality but not in desire : for instance, when a man wishes to be baptized, but by some ill-chance he is forestalled by death before receiving Baptism. And such a man can obtain salvation without being actually baptized, on account of his desire for Baptism, which desire is the outcome of faith that worketh by charity, whereby God, Whose power is not tied to visible sacraments, sanctifies man inwardly. Hence, Ambrose says of Valentinian, who died while yet a catechumen : “ I lost him whom I was to regenerate : but he did not lose the grace he prayed for.”
In the Ad Tertium, St. Thomas says, “ The sacrament of Baptism is said to be necessary for salvation in so far as man cannot be saved without, at least, Baptism of desire; “which, with God, counts for the deed”.” (August., Enarr, in Ps. 57)
The Church has always held that Baptism of water is a necessary means for salvation. However, a Baptism “in voto” can replace it when it becomes a physical or moral impossibility provided that the recipient place no obstacle nor show any contempt for the sacrament. The Fathers characterized this “baptismus fluminis” by faith, interior conversion of the heart, and a true desire to receive the sacrament : “ baptizari in voluntate.”
N.B. If it be said that this doctrine contradicts the universal law of baptism made by Christ (John, iii), the answer is that the Lawgiver has made an exception (John, xiv) in favor of those who have the baptism of desire. Neither would it be a consequence of this doctrine that a person justified by the baptism of desire would thereby be dispensed from seeking after the baptism of water when the latter became a possibility. For, as has already been explained the baptismus flaminis contains the votum of receiving the baptismus aquæ. It is true that some of the Fathers of the Church prosecute severely those who content themselves with the desire of receiving the sacrament of regeneration, but they are speaking of catechumens who of their own accord delay the reception of baptism from unpraiseworthy motives. Finally, it is to be noted that only adults are capable of receiving the baptism of desire. Reason: patet!
QUESTION & ANSWER:
1). Is the Baptism of desire a real sacrament?
NO—Although the Fathers and theologians frequently divide baptism into three kinds: the baptism of water (aquæ or fluminis), the baptism of desire (flaminis), and the baptism of blood (sanguinis), only the first is a real sacrament because “a sacrament is a kind of sign. But the other two [baptisms] are like the Baptism of water, not, indeed, in the nature of sign, but in the baptismal effect.” So, the latter two are denominated baptism only analogically, inasmuch as they supply the principal effect of baptism, namely, the grace which remits sins. Moreover, this Baptism, having not the necessary exterior sign of a sacrament, does not produce the sacramental character; since it is on account of the sensible sign that a character is imprinted.
2) What are the conditions necessary to be truly salutary?
Distinction: From the part of God— that He, first of all, gives the person actual graces, and then, for being docile to these divine movements, this recipient will have sanctifying grace or justifying grace infused by God upon his soul. For this Baptism “in voto”, which “reconciles the person with God, delivers him from original sin and infuses supernatural life”, is essentially a supernatural act that cannot be elicited by man’s natural power, nor can he dispose himself by himself for it. From the part of the recipient— With the infusion of sanctifying grace on the recipient, the person under this supernatural influence makes an act of his free will, an act of faith, and contrition. If one of these three acts is missing, that desire of baptism is neither genuine nor salutary. Hence, a catechumen who remained in sin would not be saved. For the grace of God would not be present in that soul. Grace is incompatible with sin. Consequently, not all catechumens will necessary be saved, but only those who sincerely strive to avoid sin and keep the commandment of Christ and His Church.
4) How does it differ from the simple desire of baptism?
Baptism of desire is more than the mere desire of Baptism, in a similar way that perfect contrition is more than the mere desire of confession. In both cases, the former includes the full spiritual life, that is, sanctifying grace with a “living Faith”, “working through Charity”, the latter can be the effect of a mere actual grace. In both cases too, if one fully cooperates with actual grace, Our Lord will lead this soul to the fullness of His spiritual life, because the goal and end of actual grace is always the gift of sanctifying grace.
Moreover, it comprises an act of faith and sorrow for sin. In itself the act of faith must be an act of explicit faith in the mysteries of salvation: the Trinity, the Incarnation, Redemption, the Church and the Sacraments. As such an act supposes the knowledge of Revelation, it is hard to see how it can occur in a man who has not been reached by the Church’s teaching. Must we then grant that, extraordinarily, this act of faith can have as its object only certain elements of the mysteries, and as a minimum, the existence of a God who rewards, implicitly containing the other mysteries? It is difficult to say.
5) Is the plenary absolution for sins is given also to the person who has this Baptism “in voto?
Ans.: It (possibly) does not wash away all the punishment due to sin. Thus, after baptism of desire, one might still have to pass through purgatory. Pope Innocent II ordered prayers and sacrifices for such souls. St. Thomas teaches this explicitly in his Summa, IIIa, q.68 a.2 ad.2.
VARIOUS ERRORS OF FATHER FEENEY
1* The misinterpretation of the text Jn.3: 5 i.e. it must be absolutely interpreted literally so that one must receive Baptism of water in order to win eternal life.
Refutation: His interpretation contradicts the Church’s official interpretation of the passage. The Council of Trent teaches that the grace of Baptism (res sacramenti) is absolutely necessary, without no exception whatsoever, while the exterior water (“sacramentum tantum”) is necessary “re aut voto” ---In fact or at least in desire. In other words, the Church tells us that the effect of Baptism, namely, justifying grace or sanctifying grace is necessary “sine qua non” for salvation, and that it can be obtained in three ways: 1.by Baptism of water (which is the ordinary means to obtain justification); 2. by baptism of blood; and 3. by baptism of desire. The Fathers of the Church have always taught this doctrine, and in fact, the Popes and Councils have based their declaration on this matter on their teachings.
Another reason that led Father Feeney to this error is that he, unfortunately, missed the point of the text. The whole context is actually emphasizing on the spiritual rebirth rather than the rebirth obtained by the exterior water, as he erroneously thought. If we look at the whole text, we find that within six verses, Our Lord speaks of a new birth five times (v.3,5,6,7,8), but of water only once (v.5). Explaining what He has just said in v.5, Our Lord says twice: “he who is born of Spirit,” (v.6,8) without mentioning the water anymore. Then in the rest of His discourse to Nicodemus, He explains how this new birth is by “living Faith.” Therefore, the emphases of the whole context is on the spiritual rebirth, which is the grace signified and produced by the Sacrament. This is also how St. Thomas interpreted the verse in question: “ As it is written (1 king 16:7), “ Man seeth those things that appear, but the Lord beholdeth the heart.” Now a man who desires to be “ born again of water and the Holy Ghost” by Baptism, is regenerated in the heart (i.e. spiritual rebirth), though not in body; thus of the heart, in the spirit, not in the letter; whose praise is not of man but of God.”
2.) That “God would not allow one to die in the state of grace, but not yet baptized.” “Father (Feeney) taught that God would have seen to it that those few martyrs who were reported to have died without baptism would not have left this life without baptism.”
Refutation: It must be noted that this is the precise error of Father Feeney, resulting from his excessive reaction against the liberals. From this idea he would hold later on that the state of grace was not sufficient for salvation; the character of Baptism is also absolutely required to win eternal life. Let me quote to you Fr. Laisney’s refutation on this error. He says,
“such affirmation makes liars the very person who reported the Martyrdom of these martyrs! This is a gratuitous affirmation, in opposition to the opinion if the Fathers. Father Feeney himself was aware of the novelty of this very opinion of his, thinking he was “improving (sic) upon the teaching of some of the Doctors.” In the Bread of Life, p.137. Father Feeney wrote: “ Q. What are we to say to those who believe there are such souls (souls that die in the state of justification but have not received Baptism of Water)? A. We must say to them that they are making reason prevail over Faith, and the laws of probability over the Providence of God.” The answer should rather be: We must say that they make the teachings of the Fathers of the Church, of the Doctors of the Church, of the Popes and Saints prevail upon the “improvements” of Father Feeney!
Fr. Laisney continues, “Why not simply accept the opinion of St. Cyprian, St. Cyril of Jerusalem, St. Ambrose, St. Augustine, St. Fulgence, Innocent II, Innocent III, St. Thomas Aquinas, the council of Trent, St. Catherine of Sienna, Pope Pius IX, etc…that there are such souls in Heaven? Instead of “improving upon the teaching of some Doctors,” let us rather humbly “hold fast to the doctrine of the Fathers”!”
3.) The other strange view that Fr. Feeney held is that a person who received the sacrament of Baptism but not the Blessed Sacrament is only a son of God but not of Mary, although both may enjoy the Beatific Vision in heaven. Here is a quotation of what he wrote in his book, Bread of Life, p.97-98:
“I think that Baptism makes you the son of God. I do not think it makes you the child of Mary. I think the Holy Eucharist makes you a child of Mary…What happens to those children who die between Baptism and the Holy Eucharist?…They go to the beatific Vision. They are of the Kingdom of Mary, but they are not the children of Mary. Mary is their Queen, but not their Mother. They are like little angels. There was a strong tradition in the Church that always spoke of them as “ those angels who died in infancy.” They have the beatific Vision, and they see the great Queen, but not move in as part of the Mystical body of Christ…I say: If a child dies after having received baptism, he dies as the son of God, but not yet as the child of Mary…
Refutation: As Father Laisney points out, these words are at least offensive to the pious ear. The Church rather taught that by Baptism one was incorporated into the Mystical body of Christ, and thus became not only a son of God, but also a child of Mary. Our Lady gave birth not only to the Head (Christ) but also to the members of His Mystical Body: there is not a single member of His body whose Mother she is not!
4) Father Feeney and/or his followers were led to teach confusing things about the character of baptism, saying for instance “the character is itself a sanctifying grace”!
Refutation: Briefly, the sacramental character is not at all a sanctifying grace, for they are two different realities. A character is something indelible by nature, in such a way that even if the person who receive this mark, goes to hell, he will still have that mark in hell, whereas sanctifying grace is not permanent; it can be lost by the commission of mortal sin. Moreover, the latter is the one that makes us pleasing to God and heir to the heavenly Kingdom, and not the former. Please see p.37, Baptism of Desire by Father Laisney for further argument against this unCatholic doctrine.
 Catholic Dictionary, On Baptism.
 The Feeneyite author Thomas A. Hutchinson, in his opuscule Desire and Deception, asserts that St. Ambrose knew that Valentinian had been baptized but could not reveal it. This fiction has no basis in fact. In support of his thesis, the author references a note in the Patrology of Migne, but the given reference (PL 16, no.19) is clearly a mistake. (Fr.Rulleau) ; De Consolatione in obitu Valentiani, 51-54 = PL 26, 1374-75
 St.Basil, hom.14 in S. Baptisma; St. Gragoris Nyss, Contr. Differentes Baptismus; St. Gregory Naz.; St.J. Chrysostom, hom. 1 as Illuminandus.
 Summa Theologica, III, q. 66, a.11, ad.2
 Summa Theologica, III, q. 63, a.1, ad.2
 Baptism of desire by Fr.Rulleau , pp. 43
 Fr.Rulleau’s view
 Dz. 388, Apostolicam Sedem
 For instance, Pope Innocent II, Dz.388
 IIa qu. 68 a.2 ad 1
 Letter to Dr. Coomaraswamy 2-3-83
 Brother Michael
 Reply to Verbum, Res Fidei,Feb.87,p,22