Pergamum, at one time the capital city of the Roman province of Asia Minor, was known for its temples dedicated to a variety of pagan gods. The apostle John wrote a letter to the Christians who lived in Pergamum. Recorded in Revelation 2:12-17, this letter is identified as being "the words of him who has the sharp, double-edged sword" (verse 12). This introduction held special significance for people of Pergamum. The provincial governor in that city had what was known as "the right of the sword" Rome's authority to decide which prisoners or accused persons would live or die (including Christians who refused to honor the "divine" Caesar).

John also gives the city of Pergamum an unusual designation: "I know where you live; where Satan has his throne. Yet you remain true to my name. You did not renounce your faith in me, even in the days of Antipas, my faithful witness who was put to death in your city; where Satan lives" (verse 13).
REV 2: 12-13
“And to the angel of the church in PERGAMOS write, ‘These things says He who has the sharp two-edged sword: “I know your works, and where you dwell, where SATAN'S THRONE is.
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https://www.youtube.com/watch?v=pev6u4pCqV0&;t=68s