Why do Catholics baptize infants, while some other Christian denominations wait until adulthood?
To understand when we baptize, it’s important to know what baptism is. Baptism removes original sin, and we are reborn into the family of God, adopted as His sons and daughters. We become joint heirs with Christ and sharers in his mission. Early on, baptism was given immediately upon personal conversion, such as the three thousand baptized at Pentecost. Some Christian churches today emphasize baptism specifically as personal conversion. As such, they would not baptize young children who have not yet consciously chosen to follow Christ. As the Church slowly grew, whole households were baptized together upon the deep conversion of one of the leaders (Acts 16). From this evidence, we can surmise that may have included children who were just beginning to hear the Christian message. This would not have been uncommon, especially for Jewish converts. Circumcision marked entrance into the Old Covenant for men. This occurred, without the express consent of the infants, to male children eight days after their birth.
In the second century, processes had begun to more gradually incorporate people into the Church. The basis of this “catechumenal model” is still used in parishes today for adults wishing to convert to Catholicism. The familial transmission of faith still retains an important place. Throughout his ministry, Jesus emphasized the importance of baptism for salvation. As Catholics see it, “The Church and the parents would deny a child a priceless grace of becoming a child of God were they not to confer Baptism shortly after birth. Christian parents will recognize that this practice also accords with their role as nurtures of the life that God has entrusted to them” (Catechism of the Catholic Church 1250-1251).