from
Biblical Archaeology.org:
"Helios, the Greek god of the sun (who was later often identified with Apollo, the god of light), is another ancient pagan figure whose image reverberated through monotheistic art; both Christians and Jews used the image of the Greek god of the sun in religious contexts. The Greek deity was most commonly depicted in a chariot drawn by four horses (the quadriga). The chariot represented the sun, and according to Greek mythology, the daily journey taken by the god across the sky was the source of sunlight."
In a Christian funerary context, the image of Christ as Helios is commonly interpreted as being representative of the resurrection. In early Jewish depictions, it has been hypothesized that the image of Helios, or simply the sun as in the case of the mosaic at Sepphoris, represents God’s omnipotence.
Equally well documented are images of Christ as Orpheus, particularly in the catacombs of Rome."
Christ as the Sun god (Roman: Sol Invictus; Greek: Apollo, Helios). "This mosaic part of a larger mosaic on the ceiling of the Tomb of Julli in the Vatican necropolis in Rome, is of Byzantine origin and is representative of Early Christian art. The mosaic is made of tesserae and depicts Christ as the sun god Sol Invictus in a chariot pulled by two white horses."
See also:
Christos Helios