I answer that, As stated above (Q. 63, A. 2), a character is a spiritual power ordained to certain sacred actions. Now it has been said above (A. 1; Q. 65, A. 1) that, just as Baptism is a spiritual regeneration unto Christian life, so also is Confirmation a certain spiritual growth bringing man to perfect spiritual age. But it is evident, from a comparison with the life of the body, that the action which is proper to man immediately after birth, is different from the action which is proper to him when he has come to perfect age. And therefore by the sacrament of Confirmation man is given a spiritual power in respect of sacred actions other than those in respect of which he receives power in Baptism. For in Baptism he receives power to do those things which pertain to his own salvation, forasmuch as he lives to himself: whereas in Confirmation he receives power to do those things which pertain to the spiritual combat with the enemies of the Faith. This is evident from the example of the apostles, who, before they received the fulness of the Holy Ghost, were in the "upper room . . . persevering . . . in prayer" (Acts 1:13, 14); whereas afterwards they went out and feared not to confess their faith in public, even in the face of the enemies of the Christian Faith. And therefore it is evident that a character is imprinted in the sacrament of Confirmation.
Reply Obj. 1: All have to wage the spiritual combat with our invisible enemies. But to fight against visible foes, viz. against the persecutors of the Faith, by confessing Christ's name, belongs to the confirmed, who have already come spiritually to the age of virility, according to 1 John 2:14: "I write unto you, young men, because you are strong, and the word of God abideth in you, and you have overcome the wicked one." And therefore the character of Confirmation is a distinctive sign, not between unbelievers and believers, but between those who are grown up spiritually and those of whom it is written: "As new-born babes" (1 Pet. 2:2).
Reply Obj. 2: All the sacraments are protestations of faith. Therefore just as he who is baptized receives the power of testifying to his faith by receiving the other sacraments; so he who is confirmed receives the power of publicly confessing his faith by words, as it were ex officio.
Reply Obj. 3: The sacraments of the Old Law are called "justice of the flesh" (Heb. 9:10) because, to wit, they wrought nothing inwardly. Consequently in circumcision a character was imprinted in the body only, but not in the soul. But in Confirmation, since it is a sacrament of the New Law, a spiritual character is imprinted at the same time, together with the bodily character. _______________________
SIXTH ARTICLE [III, Q. 72, Art. 6]
Whether the Character of Confirmation Presupposes of Necessity, the
Baptismal Character?
Objection 1: It seems that the character of Confirmation does not presuppose, of necessity, the baptismal character. For the sacrament of Confirmation is ordained to the public confession of the Faith of Christ. But many, even before Baptism, have publicly confessed the Faith of Christ by shedding their blood for the Faith. Therefore the character of Confirmation does not presuppose the baptismal character.
Obj. 2: Further, it is not related of the apostles that they were baptized; especially, since it is written (John 4:2) that Christ "Himself did not baptize, but His disciples." Yet afterwards they were confirmed by the coming of the Holy Ghost. Therefore, in like manner, others can be confirmed before being baptized.
Obj. 3: Further, it is written (Acts 10:44-48) that "while Peter was yet speaking . . . the Holy Ghost fell on all them that heard the word . . . and [Vulg.: 'for'] they heard them speaking with tongues": and afterwards "he commanded them to be baptized." Therefore others with equal reason can be confirmed before being baptized.
On the contrary, Rabanus says (De Instit. Cleric. i): "Lastly the Paraclete is given to the baptized by the imposition of the high priest's hands, in order that the baptized may be strengthened by the Holy Ghost so as to publish his faith."