ISB ~ Revelation 2 v9

synagogue of Satan:The perpetrators of Christian persecution in Smyrna are Jewish. Because Jews were the only ones in the Roman Empire legally exempt from worshiping the emperor and participation in the imperial cult, they could easily betray Christians to the Roman authorities for confessing Jesus as Lord (instead of Caesar) and practicing what was still an unauthorized religion in the eyes of Rome (Acts 14:2; 17:5-8). For Paul’s estimate of what constitutes a true Jew, see Rom 2:17-29.