“By reason, therefore, of this laver of repentance and knowledge of God, which has been ordained on account of the transgression of God’s people, as Isaiah cries, we have believed, and testify that that very baptism which he announced is alone able to purify those who have repented; and this is the water of life. But the cisterns which you have dug for yourselves are broken and profitless to you. For what is the use of that baptism which cleanses the flesh and body alone?
Baptize the soul from wrath and from covetousness, from envy, and from hatred; and, lo! the body is pure. For this is the symbolic significance of unleavened bread, that you do not commit the old deeds of wicked leaven. But you have understood all things in a carnal sense, and you suppose it to be piety if you do such things, while your souls are filled with deceit, and, in short, with every wickedness. Accordingly, also, after the seven days of eating unleavened bread, God commanded them to mingle new leaven, that is, the performance of other works, and not the imitation of the old and evil works. And because this is what this new Lawgiver demands of you, I shall again refer to the words which have been quoted by me, and to others also which have been passed over. They are related by Isaiah to the following effect: ‘Hearken to me, and your soul shall live; and I will make with you an everlasting covenant, even the sure mercies of David. Behold, I have given Him for a witness to the people, a leader and commander to the nations. Nations which know not Thee shall call on Thee; and peoples who know not Thee shall escape unto Thee, because of Thy God, the Holy One of Israel, for He has glorified Thee. Seek ye God; and when you find Him, call on Him, so long as He may be nigh you. Let the wicked forsake his ways, and the unrighteous man his thoughts; and let him return unto the Lord, and he will obtain mercy, because He will abundantly pardon your sins. For my thoughts are not as your thoughts, neither are my ways as your ways; but as far removed as the heavens are from the earth, so far is my way removed from your way, and your thoughts from my thoughts. For as the snow or the rain descends from heaven, and shall not return till it waters the earth, and makes it bring forth and bud, and gives seed to the sower and bread for food, so shall My word be that goes forth out of My mouth: it shall not return until it shall have accomplished all that I desired, and I shall make My commandments prosperous. For ye shall go out with joy, and be taught with gladness. For the mountains and the hills shall leap while they expect you, and all the trees of the fields shall applaud with their branches: and instead of the thorn shall come up the cypress, and instead of the brier shall come up the myrtle. And the Lord shall be for a name, and for an everlasting sign, and He shall not fail!’ (Isa_55:3 to end) Of these and such like words written by the prophets, O Trypho,” said I, “some have reference to the first advent of Christ, in which He is preached as inglorious2, obscure, and of mortal appearance: but others had reference to His second advent1., when He shall appear in glory and above the clouds; and your nation shall see and know Him whom they have pierced, as Hosea, one of the twelve prophets, and Daniel, foretold.
~ Justin Martyr- Dialogue of Justin Vol. 1