The Catechism of the Catholic Church
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; 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; 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.”
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. 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.
1296 Christ himself declared that he was marked with his Father’s seal. 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.” 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.
III. 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.
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!”;
—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;
—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: 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.
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.
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).”