Confirmation is the gift of the Holy Ghost upon the People of Christ, or the "messianic people" (those of the Messiah). The fullness of the Holy Ghost was not something reserved for Christ alone, but something He gives to His People. It is seen on Easter Sunday and even moreso on Pentecost where the Apostles were filled with the Holy Ghost and went forth into the world preaching the Gospel and baptizing - and to those who were baptized, they also received the gift of the Spirit in turn (CCC 1287).
Along with Baptism, the Laying on of Hands (aka Confirmation) are part of the initiation into Christian living and have been ever since the Catholic Church began, at Pentecost. It is mentioned in the economy of salvation in Heb. 6:2 and thus is integral to salvation.
From very early on the use of oil to anoint the recipient of Confirmation was added. Such an "anointing" is symbolic of being a Christian, for the Christ literally means the "Anointed One." To be thusly anointed is part of that which makes one a "Christian." (CCC 1289). We must also note that in the ceremony of the Sacrament of Baptism the recipient is also anointed with the sacred chrism (CCC 1241) and it is through the Sacrament of Confirmation that one acknowledges, accepts and confirms that baptismal anointing.
The anointing with the holy chrism is also symbolic of the seal of our Master upon us. Like soldiers were marked with their leader's mark and slaves with their master's - we too are marked for God in this sacrament (CCC 1295). Jesus Himself declares He is marked/sealed by the Father as well in John 6:27 "Do not work for the food which perishes, but for the food which endures to eternal life, which the Son of Man will give to you, for on Him the Father, God, has set His seal.” (NASB).
From the CCC:
THE EFFECTS OF CONFIRMATION
1302 It is evident from its celebration that the effect of the sacrament of Confirmation is the special outpouring of the Holy Spirit as once granted to the apostles on the day of Pentecost.
1303 From this fact, Confirmation brings an increase and deepening of baptismal grace:
- it roots us more deeply in the divine filiation which makes us cry, "Abba! Father!"; (Rom 8:15)
- it unites us more firmly to Christ;
- it increases the gifts of the Holy Spirit in us;
- it renders our bond with the Church more perfect (Cf. LG 11.);
- it gives us a special strength of the Holy Spirit to spread and defend the faith by word and action as true witnesses of Christ, to confess the name of Christ boldly, and never to be ashamed of the Cross: (Cf. Council Of Florence (1439): DS 1319; LG 11; 12).
1304 Like Baptism which it completes, Confirmation is given only once, for it too imprints on the soul an indelible spiritual mark, the "character," which is the sign that Jesus Christ has marked a Christian with the seal of his Spirit by clothing him with power from on high so that he may be his witness.
- Recall then that you have received the spiritual seal, the spirit of wisdom and understanding, the spirit of right judgment and courage, the spirit of knowledge and reverence, the spirit of holy fear in God's presence. Guard what you have received. God the Father has marked you with his sign; Christ the Lord has confirmed you and has placed his pledge, the Spirit, in your hearts (St. Ambrose, De myst. 7,42:PL 16,402-403).
So, who can receive this sacrament? Every baptized person who is not yet confirmed can and should receive the Sacrament of Confirmation (CCC 1306). It is obliged in Canon Law that we must receive this sacrament:
The faithful are obliged to receive this sacrament at the proper time. Parents and pastors of souls, especially pastors of parishes, are to take care that the faithful are properly instructed to receive the sacrament and come to it at the appropriate time. (CIC Canon 890)Not only are we obliged to receive this sacrament, parents and pastors are to make sure those under their care are properly instructed and come into it at the appropriate time. This is not something which we have the option to omit - nor the option to not instruct our children in and get them to the reception of the sacrament.