Of the Erythræan Sibyl, who pointed in a Prophetic Acrostic at our Lord and his Passion. The Acrostic is “Jesus Christ, Son of God, Saviour, Cross.”
Life of Constantine, with Orations · Eusebius of Caesarea
My desire, however, is to derive even from foreign sources a testimony to the Divine nature of Christ. For on such testimony it is evident that even those who blaspheme his name must acknowledge that he is God, and the Son of God if indeed they will accredit the words of those whose sentiments coincided with their own. The Erythræan Sibyl, then, who herself assures us that she lived in the sixth generation after the flood, was a priestess of Apollo, who wore the sacred fillet in imitation of the God she served, who guarded also the tripod encompassed with the serpent’s folds, and returned prophetic answers to those who approached her shrine; having been devoted by the folly of her parents to this service, a service productive of nothing good or noble, but only of indecent fury, such as we find recorded in the case of Daphne. On one occasion, however, having rushed into the sanctuary of her vain superstition, she became really filled with inspiration from above, and declared in prophetic verses the future purposes of God; plainly indicating the advent of Jesus by the initial letters of these verses, forming an acrostic in these words: Jesus Christ, Son of God, Saviour, Cross. The verses themselves are as follows:
EusVC 4.18.1