14 And if the righteous men of old, who saw in the sacraments of their time the promise of a future revelation of faith, which even then their piety enabled them to discern in the dim light of prophecy, and by which they lived, for the just can live only by faith; if, then, these righteous men of old were ready to suffer, as many actually did suffer, all trials and tortures for the sake of those typical sacraments which prefigured things in the future; if we praise the three children and Daniel, because they refused to be defiled by meat from the king's table, from their regard for the sacrament of their day; if we feel the strongest admiration for the Maccabees, who refused to touch food which Christians lawfully use; how much more should a Christian in our day be ready to suffer all things for Christ's baptism, for Christ's Eucharist, for Christ's sacred sign, since these are proofs of the accomplishment of what the former sacraments only pointed forward to in the future!
For what is still promised to the Church, the body of Christ, is both clearly made known, and in the Saviour Himself, the Head of the body, the Mediator between God and men, the man Christ Jesus, has already been accomplished. Is not the promise of eternal life by resurrection from the dead? This we see fulfilled in the flesh of Him of whom it is said, that the Word became flesh and dwelt among us. In former days faith was dim, for the saints and righteous men of those times all believed and hoped for the same things, and all these sacraments and ceremonies pointed to the future; but now we have the revelation of the faith to which the people were shut up under the law; and what is now promised to believers in the judgment is already accomplished in the example of Him who came not to destroy the law and the prophets, but to fulfill them.
Source: Reply to Faustus the Manichaean (New Advent)