Q: Why do infants who receive the sacrament of baptism have to wait until they are older to receive the sacrament of confirmation, instead of receiving them at the same time?
Delaying the sacrament of confirmation until some time after baptism preserves the candidate’s direct connection with the bishop. In the early Church, people who became Christians first were catechized over an extended period. Then they were baptized in water, anointed with oil and given the bread and wine of Eucharist all at once. The presider at this rite was the bishop, seen as the successor to the apostles, the ones sent by Christ to go and baptize all nations. However, as the Church grew, the bishop could no longer be present at all the baptisms among his flock. Thus over the centuries the initiation ritual was separated into the reception of the three sacraments of initiation that we know today. Baptism with water is performed by a local priest or deacon. The anointing with sacred chrism known as confirmation is ordinarily performed by the bishop, whenever he is able to visit a locality or candidates for confirmation are able to go to him, so that he still has a role in the initiation of all the faithful. If the candidates have reached the age of reason, confirmation is usually administered after a period of catechesis.
While this practice is standard in the Western Church (including the Roman Catholic Church), the Eastern Church continues to practice full Christian initiation all at one time. Those who are initiated in the Orthodox Churches, even if they are very young and even if the bishop is not present, are baptized with water, anointed with oil and given Eucharist all at once.