Islam has been the Ebola of religion for at least a thousand years.
To my mind, it has spread more virulently than the virus proper. A disease of the mind that panders to the very basest nature of the human psyche.
it was caught by the civilisations of Egypt, Syria, Sassanid Iran, the Eastern Roman Empire, India, etc. and destroyed all but the latter two who were wounded, but survived.
It was dying out by the 11th century when it merged with the bloodthirstiness of the Turco-Mongol races to form the Mamluk, slave dynasties and then the Seljik turks and the Ottomans and Timur-e-lang (the greatest perpetrator of genocide in history -- bigger than Attila, Genghis Khan, Mao or Stalin -- he wiped out 5% of humanity and slaughtered the ancient church of the east (the remnants of whom were the poor Christians in Mosul))