For as I passed by, and beheld your devotions, I found an altar with this inscription, TO THE UNKNOWN GOD. Whom therefore ye ignorantly worship, him declare I unto you. Beheld your devotions - Σεβασματα, The objects of your worship; the different images of their gods which they held in religious veneration, sacrificial instruments, altars, etc., etc.
To the Unknown God - ΑΓΝΩΣΤΩ ΘΕΩ. That there was an altar at Athens thus inscribed, we cannot doubt after such a testimony; though St. Jerome questions it in part; for he says St. Paul found the inscription in the plural number, but, because he would not appear to acknowledge a plurality of gods, he quoted it in the singular: Verum, quia Paulus non pluribus Diis indigebat ignotis, sed uno tantum ignoto Deo, singulari verbo usus est. Epist. ad Magn. This is a most foolish saying: had Paul done so, how much would such a begging of the question have prejudiced his defense in the minds of his intelligent judges! Oecumenius intimates that St. Paul does not give the whole of the inscription which this famous altar bore; and which he says was the following: Θεοις Ασιας και Ευρωπης και Λιβυης, Θεῳ αγνωϚῳ και ξενῳ, To the gods of Asia, and Europe, and Africa: To The Unknown and strange God. Several eminent men suppose that this unknown god was the God of the Jews; and, as his name יהוה was considered by the Jews as ineffable, the Θεος αγνωϚος may be considered as the anonymous god; the god whose name was not known, and must not be pronounced. That there was such a god acknowledged at Athens we have full proof. Lucian in his Philopatris, cap. xiii. p. 769, uses this form of an oath: νη τον αγνωϚον τον εν Αθηναις, I swear by the Unknown God at Athens. And again, cap. xxix. 180: ἡμεις δε τον εν Αθηναις αγνωϚον εφευροντες και προσκυνησαντες, χειρας εις ουρανον εκτειναντες, τουτῳ ευχαριϚησομεν ὡς καταξιωθεντες, etc. We have found out the Unknown god at Athens - and worshipped him with our hands stretched up to heaven; and we will gave thanks unto him, as being thought worthy to be subject to this power. Bp. Pearce properly asks, Is it likely that Lucian, speaking thus, (whether in jest or in earnest), should not have had some notion of there being at Athens an altar inscribed to the unknown God? Philostratus, in vit. Apollon. vi. 3, notices the same thing, though he appears to refer to several altars thus inscribed: και ταυτα Αθηνῃσι, οὑ και αγνωϚων Θεων βωμοι ἱδρυνται, And this at Athens, where there are Altars even to the Unknown Gods. Pausanias, in Attic. cap. 1. p. 4, edit. Kuhn., says that at Athens there are βωμοι Θεων των ονομαζομενων αγνωϚων, altars of gods which are called, The Unknown ones. Minutius Felix says of the Romans, Aras extruunt etiam ignotis numinibus. "They even build altars to Unknown Divinities." And Tertullian, contra Marcion, says, Invenio plane Diis ignotis aras prostitutas: sed Attica idolatria est. "I find altars allotted to the worship of unknown gods: but this is an Attic idolatry." Now, though in these last passages, both gods and altars are spoken of in the plural number; yet it is reasonable to suppose that, on each, or upon some one of them, the inscription αγνωϚῳ Θεῳ, To the unknown god, was actually found. The thing had subsisted long and had got from Athens to Rome in the days of Tertullian and Minutius Felix. See Bp. Pearce and Dr. Cudworth, to whose researches this note is much indebted.
Whom therefore ye ignorantly worship - There is here a fine paronomasia, or play on the words. The apostle tells them that (on their system) they were a very religious people - that they had an altar inscribed, αγνωϚῳ Θεῳ, to the unknown God: him therefore, says he, whom, αγνουντες, ye unknowingly worship, I proclaim to you. Assuming it as a truth, that, as the true God was not known by them, and that there was an altar dedicated to the unknown god, his God was that god whose nature and operations he now proceeded to declare. By this fine turn he eluded the force of that law which made it a capital offense to introduce any new god into the state, and of the breach of which he was charged, Acts 17:18; and thus he showed that he was bringing neither new god nor new worship among them; but only explaining the worship of one already acknowledged by the state, though not as yet known.