Acts 14:12

Verse 12. And they called Barnabas, Jupiter. Jupiter was represented as the most powerful of all the gods of the ancients. He was represented as the son of Saturn and Ops, and was educated in a cave on Mount Ida, in the island of Crete. The worship of Jupiter was almost universal. He was the Ammon of Africa, the Belus of Babylon, the Osiris of Egypt. His common appellation was, the father of gods and men. He was usually represented as sitting upon a golden or an ivory throne, holding in one hand a thunderbolt, and in the other a sceptre of cypress. His power was supposed to extend over other gods; and everything was subservient to his will, except the fates. There is the most abundant proof that he was worshipped in the region of Lycaonia, and throughout Asia Minor. There was, besides, a fable among the inhabitants of Lycaonia that Jupiter and Mercury had once visited that place, and had been received by Philemon. The whole fable is related by Ovid, (Metam. 8, 611, etc.)

And Paul, Mercarius. Mercury, called by the Greeks Hermes, was a celebrated god of antiquity. No less than five of this name are mentioned by Cicero. The most celebrated was the son of Jupiter and Msia. He was the messenger of the gods, and of Jupiter in particular; he was the patron of travellers and shepherds; he conducted the souls of the dead into the infernal regions; and he presided over orators, and declaimers, and merchants; and he was also the god of thieves, pickpockets, and all dishonest persons. He was regarded as the god of eloquence; and as light, rapid, and quick in his movements. The conjecture of Chrysostom is, that Barnabas was a large, athletic man, and was hence taken for Jupiter; and Paul was small in his person, and was hence supposed to be Mercury.

Because he was the chief speaker. The office of Mercury was to deliver the messages of the gods; and as Paul only had been discoursing, he was supposed to be Mercury.

Albert Barnes, 1834 · public domain

Verse 12 They called Barnabas, Jupiter; and Paul, Mercurius - The heathens supposed that Jupiter and Mercury were the gods who most frequently assumed the human form; and Jupiter was accustomed to take Mercury with him on such expeditions. Jupiter was the supreme god of the heathens; and Mercury was by them considered the god of eloquence. And the ancient fable, from which I have quoted so largely above, represents Jupiter and Mercury coming to this very region, where they were entertained by Lycaon, from whom the Lycaonians derived their name. See the whole fable in the first book of Ovid's Metamorphoses. As the ancients usually represented Jupiter as rather an aged man, large, noble, and majestic; and Mercury young, light, and active, the conjecture of Chrysostom is very probable, that Barnabas was a large, noble, well-made man, and probably in years; and St. Paul, young, active, and eloquent; on which account, they termed the former Jupiter, and the latter Mercury. That Mercury was eloquent and powerful in his words is allowed by the heathens; and the very epithet that is applied here to Paul, ην ὁ ἡγουμενος του λογου, he was the chief or leader of the discourse, was applied to Mercury. So Jamblichus de Myster. Init. Θεος ὁ των λογων ἡγεμων ὁ Ἑρμης. And Macrobius, Sat. i. 8: Scimus Mercurium vocis et sermonis potentem. We know that Mercury is powerful both in his voice and eloquence. With the Lycaonians, the actions of these apostles proved them to be gods; and the different parts they took appeared to them to fix their character, so that one was judged to be Jupiter, and the other Mercury.

Adam Clarke, 1831 · public domain