Reply Obj. 1: That which is both sacrament and reality—i.e. the character—and that which is reality only—i.e. the inward justification—remain: the character remains and is indelible, as stated above (Q. 63, A. 5); the justification remains, but can be lost. Consequently Damascene defined Baptism, not as to that which is done outwardly, and is the sacrament only; but as to that which is inward. Hence he sets down two things as pertaining to the character—namely, "seal" and "safeguarding"; inasmuch as the character which is called a seal, so far as itself is concerned, safeguards the soul in good. He also sets down two things as pertaining to the ultimate reality of the sacrament—namely, "regeneration" which refers to the fact that man by being baptized begins the new life of righteousness; and "enlightenment," which refers especially to faith, by which man receives spiritual life, according to Habac 2 (Heb. 10:38; cf. Habac 2:4): "But (My) just man liveth by faith"; and Baptism is a sort of protestation of faith; whence it is called the "Sacrament of Faith." Likewise Dionysius defined Baptism by its relation to the other sacraments, saying (Eccl. Hier. ii) that it is "the principle that forms the habits of the soul for the reception of those most holy words and sacraments"; and again by its relation to heavenly glory, which is the universal end of all the sacraments, when he adds, "preparing the way for us, whereby we mount to the repose of the heavenly kingdom"; and again as to the beginning of spiritual life, when he adds, "the conferring of our most sacred and Godlike regeneration."
Reply Obj. 2: As already stated, the opinion of Hugh of St. Victor on this question is not to be followed. Nevertheless the saying that "Baptism is water" may be verified in so far as water is the material principle of Baptism: and thus there would be "causal predication."
Reply Obj. 3: When the words are added, the element becomes a sacrament, not in the element itself, but in man, to whom the element is applied, by being used in washing him. Indeed, this is signified by those very words which are added to the element, when we say: "I baptize thee," etc. _______________________
SECOND ARTICLE [III, Q. 66, Art. 2]
Whether Baptism Was Instituted After Christ's Passion?
Objection 1: It seems that Baptism was instituted after Christ's Passion. For the cause precedes the effect. Now Christ's Passion operates in the sacraments of the New Law. Therefore Christ's Passion precedes the institution of the sacraments of the New Law: especially the sacrament of Baptism since the Apostle says (Rom. 6:3): "All we, who are baptized in Christ Jesus, are baptized in His death," etc.
Obj. 2: Further, the sacraments of the New Law derive their efficacy from the mandate of Christ. But Christ gave the disciples the mandate of Baptism after His Passion and Resurrection, when He said: "Going, teach ye all nations, baptizing them in the name of the Father," etc. (Matt. 28:19). Therefore it seems that Baptism was instituted after Christ's Passion.
Obj. 3: Further, Baptism is a necessary sacrament, as stated above (Q. 65, A. 4): wherefore, seemingly, it must have been binding on man as soon as it was instituted. But before Christ's Passion men were not bound to be baptized: for Circumcision was still in force, which was supplanted by Baptism. Therefore it seems that Baptism was not instituted before Christ's Passion.
On the contrary, Augustine says in a sermon on the Epiphany (Append. Serm., clxxxv): "As soon as Christ was plunged into the waters, the waters washed away the sins of all." But this was before Christ's Passion. Therefore Baptism was instituted before Christ's Passion.
I answer that, As stated above (Q. 62, A. 1), sacraments derive from their institution the power of conferring grace. Wherefore it seems that a sacrament is then instituted, when it receives the power of producing its effect. Now Baptism received this power when Christ was baptized. Consequently Baptism was truly instituted then, if we consider it as a sacrament. But the obligation of receiving this sacrament was proclaimed to mankind after the Passion and Resurrection. First, because Christ's Passion put an end to the figurative sacraments, which were supplanted by Baptism and the other sacraments of the New Law. Secondly, because by Baptism man is "made conformable" to Christ's Passion and Resurrection, in so far as he dies to sin and begins to live anew unto righteousness. Consequently it behooved Christ to suffer and to rise again, before proclaiming to man his obligation of conforming himself to Christ's Death and Resurrection.