The expression occurs neither in the Hebrew nor in the Greek of the Old Testament, nor in Apocrypha. Three passages in the Old Testament and one in Apocrypha suggest the idea conveyed in the expression. In Nu 14:27,35, Yahweh expresses His wrath against "the evil congregation" Septuagint sunagoge ponera) which He threatens to consume in the wilderness. In Ps 21 (22):16, we find, "A company of evil doers (the Septuagint sunagoge ponereuomenon) have enclosed me." In Sirach 16:6, we read, "In the congregation of sinners (the Septuagint sunagoge hamartolon) shall a fire be kindled."

Only in the New Testament occurs the phrase "synagogue of Satan," and here only twice (Re 2:9; 3:9). Three observations are evident as to who constituted "the synagogue of Satan" in Smyrna and Philadelphia.

(1) They claimed to be Jews, i.e. they were descendants of Abraham, and so laid claim to the blessings promised by Yahweh to him and his seed.

(2) But they are not regarded by John as real Jews, i.e. they are not the genuine Israel of God (the same conclusion as Paul reached in Ro 2:28).

(3) They are persecutors of the Christians in Smyrna.

The Lord "knows their blasphemy," their sharp denunciations of Christ and Christians. They claim to be the true people of God, but really they are "the synagogue of Satan." The gen. Satana, is probably the possessive gen. These Jewish persecutors, instead of being God's people, are the "assembly of Satan," i.e. Satan's people.

In Polycarp, Mar. xvii.2 (circa 155 AD) the Jews of Smyrna were still persecutors of Christians and were conspicuous in demanding and planning the martyrdom of Polycarp the bishop of Smyrna, the same city in which the revelator calls persecuting Jews "the assembly of Satan."

In the 2nd century, in an inscription (CIJ, 3148) describing the classes of population in Smyrna, we find the expression hoi pote Ioudaioi, which Mommsen thinks means "Jews who had abandoned their religion," but which Ramsay says "probably means those who formerly were the nation of the Jews, but have lost the legal standing of a separate people."

Ramsay, The Seven Churches of Asia, chapter xii; Swete, The Apocalypse of John, 31, 32; Polycarp, Mar. xiii ff.17,2; Mommsen, Historische Zeitschrift, XXXVII, 417.