When Jesus visited John of Patmos to reveal the future which we know today as The Book of Revelation, who was persecuting and murdering Christians?

It's quite obvious who Christ was talking about. Rome sits upon 7 hills and there is an 8th hill called Vatican Hill which is its own nation now. These are the hills upon which Whore of Babylon sits (Revelation 17:9-10). The many waters upon which she sits (Revelation 17:1) are the race and cultural mixers of her church (Revelation 17:15) just like Babylon. The great migration we are experiencing today is defined in Revelation 12:15 to flood the other woman, the good woman, which is our people of Christendom, the White European stock and her allies in Christ Jesus.