Justin Martyr
‘There existed, long before this time, certain men more ancient than all those who are esteemed philosophers, both righteous and beloved by God, who spoke by the Divine Spirit, and foretold events which would take place, and which are now taking place. They are called prophets. These alone both saw and announced the truth to men, neither reverencing nor fearing any man, not influenced by a desire for glory, but speaking those things alone which they saw and which they heard, being filled with the Holy Spirit. Their writings are still extant, and he who has read them is very much helped in his knowledge of the beginning and end of things, and of those matters which the philosopher ought to know, provided he has believed them. For they did not use demonstration in their treatises, seeing that they were witnesses to the truth above all demonstration, and worthy of belief; and those events which have happened, and those which are happening, compel you to assent to the utterances made by them, although, indeed, they were entitled to credit on account of the miracles which they performed, since they both glorified the Creator, the God and Father of all things, and proclaimed His Son, the Christ [sent] by Him: … But pray that, above all things, the gates of light may be opened to you; for these things cannot be perceived or understood by all, but only by the man to whom God and His Christ have imparted wisdom.’
Dialogue with Trypho, Ch. VII
Tatian
retiring by myself, I sought how I might be able to discover the truth. And, while I was giving my most earnest attention to the matter, I happened to meet with certain barbaric writings, too old to be compared with the opinions of the Greeks, and too divine to be compared with their errors; and I was led to put faith in these by the unpretending cast of the language, the inartificial character of the writers, the foreknowledge displayed of future events, the excellent quality of the precepts, and the declaration of the government of the universe as centred in one Being.
Address to the Greeks. Ch. XXIX