From the Epistle to the Hebrews
Although the authority of the Epistle to the Hebrews is doubted by some, nevertheless, as I find it sometimes thought by persons, who oppose our opinion touching the baptism of infants, to contain evidence in favour of their own views, we shall notice the pointed testimony it bears in our behalf; and I quote it the more confidently, because of the authority of the Eastern Churches, which expressly place it among the canonical Scriptures. In its very exordium one thus reads: “God, who at sundry times, and in various manners, spoke in time past unto the fathers by the prophets, has in these last days spoken to us by His Son, whom He has appointed heir of all things, by whom also He made the worlds; who, being the brightness of His glory, and the express image of His person, and upholding all things by the word of His power, when He had by Himself purged our sins, sat down on the right hand of the Majesty on high.” And by and by the writer says: “For if the word spoken by angels was steadfast, and every transgression and disobedience received a just recompense of reward, how shall we escape if we neglect so great salvation?” And again in another passage: “Forasmuch then,” says he, “as the children are partakers of flesh and blood, He also Himself likewise took part of the same; that through death He might destroy him that had the power of death, that is, the devil; and deliver them who through fear of death were all their lifetime subject to bondage.” Again, shortly after, he says: “Wherefore in all things it behooved Him to be made like His brethren, that He might be a merciful and faithful High Priest in things pertaining to God, to make reconciliation for the sins of the people.” And in another place he writes: “Let us hold fast our profession. For we have not a high priest which cannot be touched with the feeling of our infirmities; but was in all points tempted like as we are, yet without sin.” Again he says: “He has an unchangeable priesthood. Wherefore He is able also to save them to the uttermost that come unto God by Him, seeing He ever lives to make intercession for them. For such a High Priest became us, who is holy, harmless, undefiled, separate from sinners, and made higher than the heavens; who needs not daily (as those high priests) to offer up sacrifice, first for His own sins, and then for the people's: for this He did once, when He offered up Himself.” And once more: “For Christ is not entered into the holy places made with hands, which are the figures of the true; but into heaven itself, now to appear in the presence of God for us: nor yet that He should offer Himself often, as the high priest enters into the holy place every year with blood of others; (for then must He often have suffered since the foundation of the world;) but now once, in the end of the world, has He appeared to put away sin by the sacrifice of Himself. And as it is appointed unto men once to die, but after this the judgment; so Christ was once offered to bear the sins of many: and unto them that look for Him shall He appear the second time, without sin, unto salvation.”
Source: Merits and Remission of Sin, and Infant Baptism (New Advent)