Regarding the Sacrament of Confirmation, the Catechism of the Catholic Church says,
“THE SACRAMENT OF CONFIRMATION
1285 Baptism, the Eucharist, and the sacrament of Confirmation together constitute the "sacraments of Christian initiation," whose unity must be safeguarded. It must be explained to the faithful that the reception of the sacrament of Confirmation is necessary for the completion of baptismal grace [cf. Roman Ritual, Rite of Confirmation (OC), Introduction 1]. For "by the sacrament of Confirmation, [the baptized] are more perfectly bound to the Church and are enriched with a special strength of the Holy Spirit. Hence they are, as true witnesses of Christ, more strictly obliged to spread and defend the faith by word and deed" [LG 11; Cf. OC, Introduction 2].
I. Confirmation in the Economy of Salvation
1286 In the Old Testament the prophets announced that the Spirit of the Lord would rest on the hoped-for Messiah for his saving mission [cf. Isa 11:2, 61:1; Lk 4:16-22]. The descent of the Holy Spirit on Jesus at his baptism by John was the sign that this was he who was to come, the Messiah, the Son of God [cf. Mt 3:13-17; Jn 1:33-34]. He was conceived of the Holy Spirit; his whole life and his whole mission are carried out in total communion with the Holy Spirit whom the Father gives him "without measure" [Jn 3:34].
1287 This fullness of the Spirit was not to remain uniquely the Messiah's, but was to be communicated to the whole messianic people [cf. Ezek 36:25-27; Joel 3:1-2]. On several occasions Christ promised this outpouring of the Spirit,[ cf. Lk 12:12; Jn 3:5-8, 7:37-39, 16:7-15; Acts 1:8] a promise which he fulfilled first on Easter Sunday and then more strikingly at Pentecost [cf. Jn 20:22; Acts 2:1-14]. Filled with the Holy Spirit the apostles began to proclaim "the mighty works of God," and Peter declared this outpouring of the Spirit to be the sign of the messianic age [Acts 2:11, cf. 2:17-18]. Those who believed in the apostolic preaching and were baptized received the gift of the Holy Spirit in their turn [cf. Acts 2:38].
1288 "From that time on the apostles, in fulfillment of Christ's will, imparted to the newly baptized by the laying on of hands the gift of the Spirit that completes the grace of Baptism. For this reason in the Letter to the Hebrews the doctrine concerning Baptism and the laying on of hands is listed among the first elements of Christian instruction. The imposition of hands is rightly recognized by the Catholic tradition as the origin of the sacrament of Confirmation, which in a certain way perpetuates the grace of Pentecost in the Church" [Paul VI, Divinae consortium naturae, 659; cf. Acts 8:15-17, 19:5-6; Heb 6:2].
1289 Very early, the better to signify the gift of the Holy Spirit, an anointing with perfumed oil (chrism) was added to the laying on of hands. This anointing highlights the name "Christian," which means "anointed" and derives from that of Christ himself whom God "anointed with the Holy Spirit" [Acts 10:38]. This rite of anointing has continued ever since, in both East and West. For this reason the Eastern Churches call this sacrament Chrismation, anointing with chrism, or myron which means "chrism." In the West, Confirmation suggests both the ratification of Baptism, thus completing Christian initiation, and the strengthening of baptismal grace - both fruits of the Holy Spirit.
II. The Signs and the Rite of Confirmation
1293 In treating the rite of Confirmation, it is fitting to consider the sign of anointing and what it signifies and imprints: a spiritual seal.
Anointing, in Biblical and other ancient symbolism, is rich in meaning: oil is a sign of abundance and joy [cf. Deut 11:14; Pss 23:5; 104:15]; it cleanses (anointing before and after a bath) and limbers (the anointing of athletes and wrestlers); oil is a sign of healing, since it is soothing to bruises and wounds [cf. Isa 1:6; Lk 10:34]; and it makes radiant with beauty, health, and strength.
1294 Anointing with oil has all these meanings in the sacramental life. the pre-baptismal anointing with the oil of catechumens signifies cleansing and strengthening; the anointing of the sick expresses healing and comfort. The post-baptismal anointing with sacred chrism in Confirmation and ordination is the sign of consecration. By Confirmation Christians, that is, those who are anointed, share more completely in the mission of Jesus Christ and the fullness of the Holy Spirit with which he is filled, so that their lives may give off "the aroma of Christ" [2 Cor 2:15].
1295 By this anointing the confirmand receives the "mark," the seal of the Holy Spirit. A seal is a symbol of a person, a sign of personal authority, or ownership of an object [cf. Gen 38:18; 41:42; Deut 32:34; CT 8:6]. Hence soldiers were marked with their leader's seal and slaves with their master's. A seal authenticates a juridical act or document and occasionally makes it secret [cf. 1 Kings 21:8; Jer 32:10; Isa 29:11].
1296 Christ himself declared that he was marked with his Father's seal [cf. Jn 6:27]. Christians are also marked with a seal: "It is God who establishes us with you in Christ and has commissioned us; he has put his seal on us and given us his Spirit in our hearts as a guarantee" [2 Cor 1:21-22; cf. Eph 1:13, 4, 30]. This seal of the Holy Spirit marks our total belonging to Christ, our enrollment in his service for ever, as well as the promise of divine protection in the great eschatological trial [cf. Rev 7:2-3, 9:4; Ezek 9:4-6].
III. The Effects of Confirmation
1302 It is evident from its celebration that the effect of the sacrament of Confirmation is the full 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]:
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].
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 [cf. Council of Trent (1547) DS 1609; Lk 24:48-49].
1305 This "character" perfects the common priesthood of the faithful, received in Baptism, and "the confirmed person receives the power to profess faith in Christ publicly and as it were officially (quasi ex officio)" [St. Thomas Aquinas, STh III, 72, 5, ad 2].”
To learn more about the Church’s teaching on Confirmation and its celebration and participants, refer to the Catechism of the Catholic Church 1285-1321.