Castor and Pollux were twin half-brothers in Greek and Roman mythology, known together as the Dioskouroi. They were sons of Leda by two different fathers. Castor was the mortal son of Tyndareus, the king of Sparta, while Pollux was the divine son of Zeus.
When Castor was killed, Pollux asked Zeus to let him share his own immortality with his twin to keep them together, and they were transformed into the constellation Gemini. The pair were regarded as the patrons of sailors, to whom they appeared as St. Elmo’s fire.
There is an oblique reference to Castor and Pollux in the Acts of the Apostles, when the author, Luke, writing of his journeys with the apostle Paul recalls, “Three months later we set sail on a ship that had wintered at the island, an Alexandrian ship with the Twin Brothers [Dioskouroi] as its figurehead.”
It illustrates how these men, though Christian, were familiar with these Pagan gods and weren’t afraid to board a ship dedicated to them.