you will not find in the bible but you will hear it often in Christian forums. For the record it says ‘they will reign with Christ’. It does not say Christ will reign with them. Big difference. Consequently many ignore a Christian empire that lasted a thousand years. The Byzantine Empire. A big piece of the puzzle called the Apocalypse. Many pieces of the puzzle you will find in the history of the Byzantine Empire.
Watch for more pieces that fit. Blessed is the one who looks.