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 (Rm. 6:3): "All we, who are baptized in Christ Jesus, are baptized in His death," etc.

❌ Objection 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. (Mt. 28:19). Therefore it seems that Baptism was instituted after Christ's Passion.

❌ Objection 3 : Further, Baptism is a necessary sacrament, as stated above (Question [65], Article [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.