The validity of the baptism of infants is often doubted by many protestants. This is largely derived from the theology of the Anabaptists, a group that rose out of the Radical Reformation. The Schleitheim Confession, an early Swiss Anabaptist creed that was written in 1527, is quoted as saying:
"Baptism shall be given to all those who have learned repentance and amendment of life, and who believe truly that their sins are taken away by Christ, and to all those who walk in the resurrection of Jesus Christ, and wish to be buried with Him in death, so that they may be resurrected with Him and to all those who with this significance request it (baptism) of us and demand it for themselves. This excludes all infant baptism, the highest and chief abomination of the Pope."
This, of course, is contrary to the teachings of Orthodoxy, which correctly teaches that infants are perfectly capable of being in the Body of Christ. As pointed out by Origen, in his Homily to the Romans, "the Church received from the apostles the tradition of baptizing infants too."
Infant Baptism as the New Circumcision
the early church often contrasted the rite of baptism to that of circumcision. In the same way the rite of Circumcision initiated one into the nation of Israel and the Jewish people, the rite of Baptism brings one into the life of the Church.
"In him you were also circumcised with a circumcision not performed by human hands. Your whole self ruled by the flesh was put off when you were circumcised by Christ, having been buried with him in baptism, in which you were also raised with him through your faith in the working of God, who raised him from the dead." Colossians 2:11-12
This line of reasoning was carried on by the Holy Fathers. For example, Hilary of Poitiers, Augustine, and Cyprian all expressed the idea that Circumcision is connected to the Rite of Baptism.
Salvific Power of Baptism
The view that baptism is one rational and personal affirmation of faith is called Credobaptism and is shared by most Baptists and most and Evangelicals today. One can rightfully claim that the postion known as Credobaptism is a "recent" invention, rather than the position of the 1st century Church. Furthermore, this position is not shared by the Orthodox Church since the the New Testement in several areas specifically teaches that baptism is a rebirth, a nessity for salvation, and has the ability to wash away sins. For example:
"He that believeth and is baptized shall be saved; but he that believeth not shall be damned." Mark 16:16
"Jesus replied, 'Very truly I tell you, no one can see the kingdom of God unless they are born again.'How can someone be born when they are old?' Nicodemus asked. 'Surely they cannot enter a second time into their mother’s womb to be born!' Jesus answered, 'Very truly I tell you, no one can enter the kingdom of God unless they are born of water and the Spirit'." John 3:3-5
"And now why do you wait? Rise and be baptized and wash away your sins,calling on his name." Acts 22:16
"And that is what some of you were. But you were washed, you were sanctified, you were justified in the name of the Lord Jesus Christ and by the Spirit of our God." 1 Corinthians 6:11
Personal Death Within Christ
The Church has always taught that the means of baptism's power to give rebirth is that of a personal death in Christ. By taking part in the rite of baptism, one is actually mystically dying within Christ and is then being resurrected with him. Support of this, the New Testement proclaims:
"We were therefore buried with him through baptism into death in order that, just as Christ was raised from the dead through the glory of the Father, we too may live a new life." Romans 6:4
"for all of you who were baptized into Christ have clothed yourselves with Christ." Gal. 3:27
"And when you were baptized, it was the same as being buried with Christ. Then you were raised to life because you had faith in the power of God, who raised Christ from death." Colossians 2:12
The Family As One Flesh
The need for infant baptism can also be deduced from Trinitarian theology and the Church's teachings in regard to the family. In accordance to Genesis 2:24, a man and a women make up one flesh. This is because the family unit is an icon of the Trinity, reflecting the image of God. John 10:30 correctly points out that the Father and Son are one. Thus, since the family is an icon of the Trinity, the children of a family are considered to be of one flesh with their parents. Because of this, it becomes a preference not to receive person individually but communally into the Church via baptism. This of course would require children and infants to be present.
Possible Biblical References
Though there is no direct examples of infants being baptized in the Bible, there are numerous indirect references.
"Jesus said, 'Let the little children come to me, and do not hinder them, for the kingdom of heaven belongs to such as these.'" Matthew 19:14 (Note: Christ clearly says that baptism is necessary for salvation. "He that believeth and is baptized shall be saved" Mark 16:16).
"People were also bringing babies to Jesus for him to place his hands on them. When the disciples saw this, they rebuked them. But Jesus called the children to him and said, 'Let the little children come to me, and do not hinder them, for the kingdom of God belongs to such as these. Truly I tell you, anyone who will not receive the kingdom of God like a little child will never enter it.'" Luke 18:15-17 (Note: Here the people bring their infants to the Christ in the hope that He will bless them. A blessing is understood by the Church to mean an impartation of grace. Thus, the reception of grace is not dependent on an "age of reason".)
"Peter replied, “Repent and be baptized, every one of you, in the name of Jesus Christ for the forgiveness of your sins. And you will receive the gift of the Holy Spirit. The promise is for you and your children and for all who are far off—for all whom the Lord our God will call.” Acts 2:38-39
"When she and the members of her household were baptized, she invited us to her home. 'If you consider me a believer in the Lord,' she said, 'come and stay at my house.' And she persuaded us." Acts 16:15
"At that hour of the night the jailer took them and washed their wounds; then immediately he and all his household were baptized." Acts 16:33
Ethical Implications of Credobaptism
Origen, Homily on Romans, V:9 (A.D. 244).