Baptism is the means by which we are made children of God and have original sin removed from our souls. While all of the Sacraments were instituted by our Lord Jesus Christ, Baptism itself is explicitly mentioned several times in Sacred Scripture:
"Jesus answered, and said to him: 'Amen, amen I say to thee, unless a man be born again, he cannot see the kingdom of God.' Nicodemus saith to him: 'How can a man be born when he is old? can he enter a second time into his mother's womb, and be born again?' Jesus answered: 'Amen, amen I say to thee, unless a man be born again of water and the Holy Ghost, he cannot enter into the kingdom of God'" (John 3:3-5).
"Going therefore, teach ye all nations; baptizing them in the name of the Father, and of the Son, and of the Holy Ghost" (Matthew 28:19).
"But Peter said to them: 'Do penance, and be baptized every one of you in the name of Jesus Christ, for the remission of your sins: and you shall receive the gift of the Holy Ghost. For the promise is to you, and to your children, and to all that are far off, whomsoever the Lord our God shall call'" (Acts 2:38-39).
Proper Matter and Form of Baptism
Our Lord Jesus Christ told His disciples the exact formula that must be used for a valid Baptism when He said: “All power is given to me in heaven and in earth. Going therefore, teach ye all nations; baptizing them in the name of the Father, and of the Son, and of the Holy Ghost. Teaching them to observe all things whatsoever I have commanded you: and behold I am with you all days, even to the consummation of the world" (Matthew 8:18-20).
It is vitally important that each and every baptized person be baptized in the Name of the Father, the Son, and the Holy Ghost. To be baptized only in the name of Jesus does not constitute an authentic baptism because it does not follow the formula established by Jesus Himself. All Sacraments must have two proper parts – form and matter. In Baptism, for example, we must be baptized with water. Secondly, baptisms must have the proper form meaning that water must be poured over the individuals head three times while saying the words: “I baptize you in the name of the Father, and of the Son, and of the Holy Spirit.”
Christ Instituted the Sacrament of Baptism
All seven Sacraments were instituted by our Lord Jesus Christ. While some may incorrectly think that St. John the Baptist instituted the Sacrament of Baptism or that the Apostles instituted the Sacrament of Extreme Unction, the Church’s clear teaching is that the Lord Jesus Christ alone instituted all Sacraments as stated in the Catechism of the Council of Trent:
“Since human justification comes from God, and since the Sacraments are the wonderful instruments of justification, it is evident that one and the same God in Christ, must be acknowledged to be the author of justification and of the Sacraments.”
St. John the Baptist preached a "baptism of repentance" which called for those who received it to repent. It was not the Sacrament of Baptism which our Lord instituted. It was more of what we would consider a sacramental. For that reason, the Apostles baptized those who had received the Sacramental given by St. John the Baptist with the actual Sacrament of Baptism.
St. Jerome writes, “Those who were baptized with John's baptism needed to be baptized with the baptism of our Lord." Likewise, St. Augustine says, “Our sacraments are signs of present grace, whereas the sacraments of the Old Law were signs of future grace.” In Acts 19:1-5, St. Paul baptizes several people that were previously baptized in repentance by John. Why? They were baptized not only because they did not know of the Holy Ghost but also because they had not received the baptism of Christ.
How Does Baptism Work?
In Sacramental Theology, the Church teaches that the Sacraments work ex opere operato (latin meaning "from the work performed"), which was defined by the Council of Trent. The Council of Trent dogmatically defined that grace is always conferred by a Sacrament, "in virtue of the rite performed and not as a mere sign that grace has already been given, or that the sacrament stimulates the faith of the recipient and thus occasions the obtaining of grace, or that what determines the grace is the virtue of either the minister or recipient of a sacrament."
Thus, provided there is no obstacle placed in the way (e.g. improper matter used, the wrong words were said, the minister did not have the proper intention) every Baptism properly administered confers the grace intended by the Sacrament. The reception of Baptism does not depend on the sanctity of the individual priest conferring it since it is ultimately Christ acting through all the Sacraments in the conferring of grace.
Baptism first and foremost clears all sin from our soul. This is why we are baptized – we want the sin of Adam (original sin) washed away. Every human person aside from the Blessed Virgin Mary was conceived with original sin. Do note, that our Lord was also conceived without original sin but He was a divine person, not a human person. And St. John the Baptist was born without original sin but he was conceived with original sin. He was cleansed with original sin when he leapt in his mother's womb, a miracle we remember as part of the Visitation of Mary to Elizabeth.
Through Baptism original sin is washed away, and at the same time, if we are baptized after having committed sins ourselves (actual sin) those sins are washed away as well along with any temporal punishments for them. If we would die immediately after Baptism, our soul would go straight to Heaven.
Most Protestants view baptism as the covering up of our sins. That is not correct. Baptism completely washes the soul clean. We receive sanctifying grace, which raises us up to a supernatural level; Baptism regenerates and saves the person. In this respect, an indelible mark is placed on the soul that initiates him into the life of the Church, and allows him to receive the other Sacraments. Even if a baptized person goes to Hell, this mark will remain for all eternity on the soul.
Through Baptism was become sharers in the Divine Nature of the Blessed Trinity. We become sons of God and tabernacles of the Most Holy. We become temples for the Holy Spirit. In Baptism we are born again as St. Peter writes of the divine sonship in Baptism as “…Being born again not of corruptible seed, but incorruptible, by the word of God who liveth and remaineth for ever” (1 Peter 1:23). In Baptism we are buried in Christ so that we might rise with Him (cf. Romans 6:3-4).
The Catechism of the Council of Trent states, “…it should be taught that by virtue of this Sacrament we are not only delivered from what are justly deemed the greatest of all evils, but [we] are also enriched with invaluable goods and blessings. Our souls are replenished with divine grace, by which we are rendered just and children of God and are made heirs to eternal salvation."
Prefiguring Images of Baptism in the Old Testament
God chose water, the humble source of life, to be the matter by which mankind would be born from above. Through the Great Flood and Noah’s Ark, the Church sees a prefiguring image of salvation through Baptism. And through “the crossing of the Red Sea” Israel was liberated from slavery just as the baptized are saved from slavery through sin. Likewise, Moses was pulled out of the waters as a baby, just as we are pulled from sin through the waters of Baptism.
Why Was Christ Baptized by St. John?
We find in Christ's Baptism a two fold purpose. He clearly did not need to receive forgiveness of sins because He is God Himself and can not sin. But He chose to undergo the ritual first for our own edification so that we might follow His example, and secondly so that He might in a sense given the waters of Baptism their power: “The Lord was baptized, not to be cleansed Himself but to cleanse the waters, so that those waters, cleansed by the flesh of Christ which knew no sin, might have the power of Baptism. Whoever comes, therefore, to the washing of Christ lays aside his sins” (St. Ambrose).
Baptism by immersion is unnecessary for Salvation. For around 12 centuries, immersion was the common form practiced in the Catholic Church. However, St. Thomas Aquinas, who lived in the 13th Century, states, “Baptism can be conferred by sprinkling and also by pouring.” Tertullian, who was born c. 160 AD, said that Baptism is a “sprinkling with any kind of water” (De Bapt., Ch. 6). The Didache (The Teaching of the Apostles) holds that baptismal water may be poured when there is not enough water for immersion. St. Thomas Aquinas also states that the three thousand converts baptized by St. Peter on the first Pentecost were most likely not baptized by immersion; there was not enough water in Jerusalem at the time. He also says that it is highly unlikely that the jailer baptized in the prison at Philippi or the Gentiles in the home of Cornelius were immersed in water.
Is Baptism Necessary for Salvation?
Yes, the Council of Trent states that Baptism is necessary for salvation. "Canon 5. If anyone says that baptism is optional, that is, not necessary for salvation, let him be anathema." (Canons On Baptism, Session VII, Council of Trent).
We also hear from Our Lord: "'Amen, amen I say to thee, unless a man be born again, he cannot see the kingdom of God" (John 3:5). He is speaking of Baptism.
What though of those who have died? We entrust them all to the Sacred Heart of our Lord Jesus Christ. God has bound salvation to the sacrament of Baptism, but He Himself is not bound by His sacraments. Pray for all departed souls, that they were able to be saved before death by a miraculous intervention of God.
Infant Baptism
The Church has always taught that the Sacrament of Baptism can and should be conferred on children. In Baptism we are “born again”; it is the start of the life that continues in the next. Since Baptism is the start of life, a child should be baptized as soon as possible that they might have a share in divine sonship. As Jesus says, “Suffer the little children to come unto me, and forbid them not; for of such is the kingdom of God.” (Mark 10:14).
In the Gospel Jesus instructs us to go forth and baptize the whole world – not just adults. St. Paul baptized whole families and it is most likely there was at least one child in those families (Acts 16:15; 1 Cor. 1:16). The Third Council of Carthage (253 AD) with St. Cyprian taught that infants should be baptized as soon as possible after birth. The Council of Milevis in 416 AD taught the necessity of baptism for infants. This same position has been reaffirmed at the Fourth Lateran Council as well as the Councils of Vienne, Florence, and Trent. See the Fifth Session of the Council of Trent for more information.
Are Non-Catholic Baptisms Valid?
The Church may accept the validity of most Protestant Baptisms, since a validly ordained minister is not required for this particular Sacrament, so long as those Baptisms used the proper matter, form, and intention. For this reason, the alleged baptisms of certain groups like the Mormons or Jehovah's Witnesses are not valid for lack of proper words and proper intention. The issue with Protestant Baptisms for other sects is whether the baptizer had the right intention. Due to many protestants having erroneous conceptions on original sin and the role of Baptism, doubt may exist on the validity of such baptisms. Anyone seeking to convert who was baptized in a protestant denomination should consult with a priest to determine if they need to be conditionally baptized.
The Church teaches very unequivocally that for the valid conferring of the sacraments, the minister must have the intention of doing at least what the Church does. This is laid down with great emphasis by the Council of Trent (sess. VII). The opinion once defended by such theologians as Catharinus and Salmeron that there need only be the intention to perform deliberately the external rite proper to each sacrament, and that, as long as this was true, the interior dissent of the minister from the mind of the Church would not invalidate the sacrament, no longer finds adherents. The common doctrine now is that a real internal intention to act as a minister of Christ, or to do what Christ instituted the sacraments to effect, in other words, to truly baptize, absolve, etc., is required. This intention need not necessarily be of the sort called actual. That would often be practically impossible. It is enough that it be virtual. Neither habitual nor interpretative intention in the minister will suffice for the validity of the sacrament. The truth is that here and now, when the sacrament is being conferred, neither of these intentions exists, and they can therefore exercise no determining influence upon what is done. To administer the sacraments with a conditional intention, which makes their effect contingent upon a future event, is to confer them invalidly. This holds good for all the sacraments except matrimony, which, being a contract, is susceptible of such a limitation.
Source: Catholic Encyclopedia1962 Rite of Baptism:
To see the comparison of Sacrament Baptism in the Old and New Rites, see my post on Baptism Old vs. New Rite. Two videos of the 1962 Rite follow: