The Catechism of the Catholic Church in paragraph 1282 says “Since the earliest times, Baptism has been administered to children, for it is a grace and a gift of God that does not presuppose any human merit;”. We can infer from this statement that the Church recognizes that infant baptism has been practiced since the earliest days of the Church. Some will argue that in the Apostles time they did not baptize infants, that the practice of infant baptism was a later invention and thus not biblical. So, what evidence do we have that Infant Baptism was practiced by the first Christians?
In Paul’s letter to the Colossians he draws the parallel between baptism and circumcision:
11 In him also you were circumcised with a circumcision made without hands, by putting off the body of flesh in the circumcision of Christ; 12 and you were buried with him in baptism, in which you were also raised with him through faith in the working of God, who raised him from the dead.Colossians 2:11-12
Circumcision and took place just after the birth of the child. Paul is directly drawing the conclusion that baptism is the new circumcision, thus fulfilling that practice. Just as circumcision was performed on the infant not by its faith but by the faith of the parents, baptism is to be performed on infants.
We find extra biblical evidence from the early church confirming this practice from the very beginning. St. Irenaeus of Lyons wrote in 189 AD:
For he came to save all through himself-all, I say, who through him are born again to God infants, and children, and boys, and youths, and old men.Against Heresies 2:22:4 AD 189
We know from John Chapter 3 to be born again you must be born of water (baptism) and the spirit. Thus St. Irenaeus and other prominent early Christians taught very early that infants should be included in baptism.