Etsi multa
Etsi multa is a papal encyclical that was published by Pope Pius IX on November 21, 1873.
The encyclical claimed that there were three campaigns being waged against the Church at the time:
It condemned Freemasonry, which was blamed for the widespread attack on the Catholic Church, accusing it of being "the Synagogue of Satan".
In all the Bible, the same expression "synagogue of Satan" is uniquely referenced in Apocalypse of John 2:9 and 3:9, in the messages addressed by the Apostle and Evangelist to the Seven churches of Asia, including their respective guardian angels.