Greek and Roman prophetesses predating the Christ were known as Sibyls. Due to the fact that their prophecies often support Christian belief, the early Christians believed that God had planted seeds of truth in the Greek and Roman cultures through the sibyls.

We must also mention what the ancient and exceedingly remote Sibyl, whom Plato and Aristophanes, and others besides, mention as a prophetess, taught you in her oracular verses concerning one only God. And she speaks thus: There is one only unbegotten God, omnipotent, invisible, most high, all-seeing, but Himself seen by no flesh. Then elsewhere thus: But we have strayed from the Immortal's ways, and worship with a dull and senseless mind idols, the workmanship of our own hands, and images and figures of dead men. And again somewhere else: Blessed shall be those men upon the earth who shall love the great God before all else, blessing Him when they eat and when they drink; trusting it, this their piety alone. Who shall abjure all shrines which they may see, all altars and vain figures of dumb stones, worthless and stained with blood of animals, and sacrifice of the four-footed tribes, beholding the great glory of One God. These are the Sibyl's words.

And you may in part easily learn the right religion from the ancient Sibyl, who by some kind of potent inspiration teaches you, through her oracular predictions, truths which seem to be much akin to the teaching of the prophets… she there uttered her oracular sayings in a city called Cumae, six miles from Baiae, where the hot springs of Campania are found. …And in the middle of the basilica they showed us three receptacles cut out of one stone, in which, when filled with water, they said that she washed, and having put on her robe again, retires into the inmost chamber of the basilica, which is still a part of the one stone; and sitting in the middle of the chamber on a high rostrum and throne, thus proclaims her oracles. Justin Martyr (A.D. 160) Ante-Nicene Fathers vol.1 pg. 289

"Those whom we now call prophetic persons we should rightly name divine. And not least would we say that they are divine, and are raised to the prophetic ecstasy by the inspiration and possession of God, when they correctly speak of many and important matters, and yet know nothing of what they are saying," - plainly and manifestly referring to the prophecies of the Sibyl.

As I said, the most ancient and time-honored Sibyl, whose books are preserved in all the world, and who by some kind of potent inspiration both teaches us in her oracular utterances concerning those that are called gods, that have no existence; and also clearly and manifestly prophesies concerning the predicted advent of our Savior Jesus Christ, and concerning all those things which were to be done by Him. Justin Martyr (A.D. 160) Ante-Nicene Fathers vol.1 pg. 289

But men of God carrying in them a holy spirit and becoming prophets, being inspired and made wise by God, became God-taught, and holy, and righteous. Wherefore they were also deemed worthy of receiving this reward, that they should become instruments of God, and contain the wisdom that is from Him, through which wisdom they uttered both what regarded the creation of the world and all other things. For they predicted also pestilences, and famines, and wars. And there was not one or two, but many, at various times and seasons among the Hebrews; and also among the Greeks there was the Sibyl; and they all have spoken things consistent and harmonious with each other, both what happened before them and what happened in their own time, and what things are now being fulfilled in our own day: wherefore we are persuaded also concerning the future things that they will fall out, as also the first have been accomplished. Theophilus (A.D. 180) Ante-Nicene Fathers vol.2 pg.97

And similarly did the Sibyl speak, when she declared that wrath would come on the world. She says: "When are fulfilled the threats of the great God, with which He threatened men, when formerly in the Assyrian land they built a tower, and all were of one speech, and wished to rise even till they climbed unto the starry heaven, then the Immortal raised a mighty wind and laid upon them strong necessity; for when the wind threw down the mighty tower, then rose among mankind fierce strife and hate. One speech was changed to many dialects, and earth was filled with divers tribes and kings." Theophilus (A.D. 180) Ante-Nicene Fathers vol.2 pg.106

The Apostle Paul will show, saying: "Take also the Hellenic books, read the Sibyl, how it is shown that God is one, and how the future is indicated. And taking Hystaspes, read, and you will find much more luminously and distinctly the Son of God described, and how many kings shall draw up their forces against Christ, hating Him and those that bear His name, and His faithful ones, and His patience, and His coming." Then in one word he asks us, "Whose is the world, and all that is in the world? Are they not God's?" Wherefore Peter says, that the Lord said to the apostles: "If any one of Israel then, wishes to repent, and by my name to believe in God, his sins shall be forgiven him, after twelve years. Go forth into the world, that no one may say, We have not heard." Clement of Alexandria (A.D. 195) Ante-Nicene Fathers vol.2 pg.490