In the Greek and Roman world, the Sibyls were elderly prophetesses who usually prophesied in a state of ecstasy (trance-like). The writing attributed to them often contain various prophecies that support Christian beliefs. Modern scholars usually explain this fact by saying that either the Jews or the Christians tampered with the Sibylline Oracles. The problem is, that there is no evidence of this. In fact, the early Christians believed that God had planted seeds of truth in the Greek and Roman cultures through the Sibyls. Obviously God dealt with the nations at some time, for Romans 1 says that “God gave them up” (Rom 1:26). He could not have given up on people that he never made any effort to guide. Balaam is one example of a Gentile prophet (Num 22:6). Melchizedik (Gen 14:18-20) and Jethro are possibly two others (Ex 18:12-20).
In contrast to the bishops at Carthage that gave us our canon in 397, the brethren 200 years earlier spoke quite favorably of the sibys, and believed that the things they spoke were true. Here are some examples
The Sibyl and Hystaspes said that tehre would be a dissolution of all corruptible things by God. Justin Martyr (c. 160). Early Church Fathers (ECF), Vol 1:169.
[Addressed to pagans:] You may in part easily learn the right religion from the ancient Sibyl. For, by some kind of powerful inspiration, she teaches you. Through her oracular predictions, she teaches truths that seem to be similar to the teaching of the prophets. They say that she was of Babylonian lineage, being the daughter of Berosus, who wrote the the History of the Chaldeans. Justin Martyr (c. 160), ECF, Vol 1:288.
But I have to remark further, that the Sibyl also has said concerning them that they worship the images of decesased kings. Melito (c. 170), ECF Vol 8:752.
Also, among the Greeks there was the Sibyl. They all have spoken things consistent and harmoneous with each other. Theophilus (c. 180), ECF Vol 2:97.
From that time [i.e., of the tower of Babel], Gond confused the languages of men, giving to each a different dialect. And the Sibyl speaks similarly of this…”In the Assyrian land they built a tower, and all were of one speech, and wished to rise even until they climbed unto the starry heavens.” Theophilus (c. 180), ECF Vol 2:106.
The Sibyl was a prophetess among the Greeks and the other nations. In the beginning of her prophecy, she reproaches the race of men, saying,…”Do you not tremble, nor fear God Most High?…There is only one uncreated God, who reigns alone, all-powerful, very great, from whom nothing is hid.” Theophilus (c. 180), ECF Vol 2:108, 109.
It is manifestly from the prophetess of the Hebrews [i.e., the Sibyl] who prophesies in the following manner: “What flesh can see with the eye the celestial, the true, the immortal God, who inhabits the vault of heaven?” Clement of Alexandria (c. 195), ECF Vol 2:192
Marcus Varro [an ancient Roman writer]…says that the Sibylline Books were not the production of one Sibyl only. Rather, they were called by one name, Sibylline, because all the prophetesses were called Sibyls by the ancients… So all these Sibyls proclaim one God….Now, in these verses that the ambassadors brought to Rome, there are these testimonies respecting the one God: “One God, who is alone, most mighty, uncreated.” This is the only supreme God, who made the heaven, and decked it with lights. “But there is only one God of pre-eminent power, who made the heaven, the sun, the stars, the moon, the fruitful earth, and the waves of the water of the sea.” …”Worship Him who is alone the ruler of the world, who alone was and is from age to age.” Also, another Sibyl, whoever she was, said that she conveyed the voice of God to men. On His behalf, she said: “I am the one only God, and there is no other God.” Lactantius (c. 304-313), ECF Vol 7:15, 16.
There is a Son of the Most High God, who is possessed of the greatest power. This is shown not only by the unanimous utterance of the prophets, but also by…the predictions of the Sibyls…The Erythraean Sibyl, in the beginning of her poem (which she began with “the Supreme God”), proclaims the Son of God as the leader and commander of all, in the following verses: “The Nourisher and Creator of all things, who placed the sweet breath in all, and made God the Leader of all.” And again, at the end of the same poem: “But whom God gave for faithful men to honor.” And another Sibyl declares that He should be known: “Know Him as your God, who is the Son of God.” Lactantius (c.304-313), ECF Vol 7:105.
The Sibyl had foretold in advance that the miracle would take place, whose verses are related to this effect: “With five loaves at the same time, and with two fishes, He will satisfy five thousand men in the wilderness.”…And again, another says, “He will walk on the waves. He will release men from disease. He will raise the dead and drive away many pains. And from the bread of one pouch, there will be a satisfying of men.” Being refuted by these testimonies, some are accustomed to fall back on the claim that these poems were not written by the Sibyls, but were invented and composed by our own writers, instead. However, he who has read Cicero, Varro, and other ancient writers will assuredly not think this. For they make mention of the Erythraean and the other Sibyls, from who books we bring forth these examples. And those authors died before the birth of Christ according to the flesh. However, I do not doubt that in former times these poems were regarded as ravings. For, at that time, no one understood them…. Therefore, they were neglected for many ages. But, they received attention after the birth and passion of Christ. Lactantius (c. 304-313), ECF Vol 7:116.
The Sibyl also showed that the same things would happen: “He will afterwards come into the hands of the unjust and the faithless. And they will inflict blows with impure hands on God.” Lactantius (c. 304-313), ECF Vol 7:120.
[James J. continues] While the early Christian writers regarded the pagan oracles with contempt and empowered by demons, they nevertheless spoke favorably of the Sibyls. For example, Lactantius, when speaking of the pagan oracles, said, “However, all these things are deceptions. For since demons have some foreknowledge of the arrangements of God (having been His ministers), they interpose themselves in these matters… so it will appear that they themseles are doing it” (ECF, Vol 7:66). So we have very strong evidence from the earliest Christian orthodox writers, that in contrast to the pagan oracles such the ones at Delpi and Apollo, the Sibyls were highly regarded among the brethren. Justin Martyr, one of the very oldest writers, even said they had some kind of powerful inspiration. Considering the early evidence, it seems to be overreaching to summarily dismiss it as fiction.