John Calvin Commentary Acts 28:11

"And after three months we set sail in a ship of Alexandria which had wintered in the island, whose sign was The Twin Brothers." — Acts 28:11 (ASV)

In a ship of Alexandria. By these words, Luke makes clear that the former ship was either sunk, or else so torn and battered, that it was of no use afterwards; by which the severity of the shipwreck is more apparent. And he explicitly states that the badge of the Alexandrian ship, in which they were carried to Rome, was Castor and Pollux, so that we may know that Paul was not granted the freedom to sail with those like himself, but was forced to board a ship dedicated to two idols.

The ancient poets fabled that Castor and Pollux were the offspring of Jupiter and Leda, for which reason they are called διοσκουροι in Greek—a word Luke uses here, meaning Jupiter’s sons. Furthermore, they said that Castor and Pollux are the sign in the zodiac called Gemini.

There was also another superstition among the mariners: that those luminous exhalations which appear in tempests were Castor and Pollux themselves. Therefore, in the past, they were considered sea gods and were invoked, just as today Nicholas, Clement, and similar figures are. Indeed, just as in Popery they retain the old errors, only changing the names, so today they worship these exhalations under the name of Saint Hermes or Saint Ermus. And because if one exhalation appears alone, it is a sorrowful omen, but if two appear together (as Pliny writes), they foretell a prosperous voyage. So that the Alexandrian mariners might have both Castor and Pollux favoring them, they had both as the badge of their ship. Therefore, as far as the mariners were concerned, the ship was polluted with wicked sacrilege; but because Paul did not choose it voluntarily, he was not polluted by it.

And surely, since an idol is nothing, it cannot infect God’s creatures to prevent the faithful from using them purely and lawfully. We must certainly think that all those defilements with which Satan attempts to stain God’s creatures through his deceptions are washed away only by a good and pure conscience, while the wicked and ungodly defile those things that are pure in themselves, even if they only touch them.

Finally, Paul was no more defiled by boarding this ship than when he observed the altars at Athens, because, being free from all superstition, he knew that all the rites of the Gentiles were nothing but illusions. Furthermore, the men could not think that he consented to that profane error, for if he had been required to offer any worship to Castor and Pollux, even if only for appearance’s sake, he would rather have died a thousand deaths than yield even once.

Therefore, because he did not need to fear any offense, he boarded the ship without further delay. Undoubtedly, he did this with a heavy heart and inner sorrow, because he saw the honor due to God alone being given to empty fabrications. Therefore, this should be counted among his trials, because he had as his guides those who thought they were governed by idols and had committed their ship to their protection.