Superstition always goes to the darkest places of the mind of fear-filled believers ... grasps at evil images and points OUTWARD! Christianity stole the number 666 from religion that came long before Christianity.
She led him to a nearby museum where she showed him a seventh-century BCE mortuary stele known as the Stele of Ankh-ef-en-Khonsu (Crowley later termed it the "Stele of Revealing"); Crowley was astounded, for the exhibit's number was 666, the number of the beast in Christian belief.
Notice it says the EXHIBIT's number was 666 not the 7th century BC stele. As if you can believe anything from Crowley anyway.
The origin of the 666 does predate Rome but is also found all over Rome including the name 'vicar of christ' in Latin = 666
666 has been the number total of the gods of Babylon then transferred to Rome. Babylon's priests wore an amulet
There are many more identifiers in the Bible of the beast at Rome. If it were 666 alone this would just be interesting but nothing conclusive.