Why should we baptize newborn babies?
Baptism is conferred upon infants to free them from original sin, to initiate them into the Church as Christians, and to give them the supernatural grace of God that will allow them to be formed in sanctity. Baptism is the gateway to the other sacraments, and so it prepares the child for later reception of confirmation and the Eucharist, among other sacraments. The Catechism of the Catholic Church states:
Born with a fallen human nature and tainted by original sin, children also have need of the new birth in baptism to be freed from the power of darkness and brought into the realm of the freedom of the children of God, to which all men are called. The sheer gratuitousness of the grace of salvation is particularly manifest in infant baptism. The Church and the parents would deny a child the priceless grace of becoming a child of God were they not to confer baptism shortly after birth (1250).