Confirmation began as one and the same sacrament as baptism. While it is true that whole families were brought into the Church at once (Acts 16:15, 31-34), at this time, adult baptism was the norm. At the Easter Vigil, deacons would baptize converts who would then go immediately to their bishop, who was present at the baptism, and the bishop would confirm (i.e. acknowledge) their baptism. With baptism complete, these neophytes were brought to the Eucharistic table for the first time.
This original practice changed over the centuries: Once Christianity was entrenched, baptism became primarily a sacrament of infants, those born into Christianity and baptized at their birth, rather than of adult converts baptized at the Easter Vigil.
300s: As Christianity continued to grow, bishops could no longer be at every baptism. Instead, they would come later to confirm those already baptized. We can already see a president for this separation between baptism and confirmation at the time of the Apostles (Acts 8:14-17). Eventually, confirmation and first Eucharist became sacraments associated not with infants but with older youths.
1000s: Confirmation and First Eucharist became separate rites from each other.
Early 1900s: Many Catholics, while having received baptism, confirmation, and First Eucharist, were not receiving Communion regularly. Pope Pius X moved First Communion from after confirmation to around age seven. This was done in hopes of instilling the habit of regular Communion from an early age, and today many Catholics do receive Eucharist regularly. Thus, First Communion now normally precedes confirmation.
Late 1900s: The RCIA, the Rite of Christian Initiation of Adults, revives the original sacramental order. Since RCIA candidates are confirmed at the Easter Vigil, the bishop appoints delegates, parish pastors, to confirm in his absence, for he cannot be at all of the parishes in a diocese in one evening. Outside of the RCIA, the Church typically still follows the order recommended by Pope Pius X.
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