Tom Holland in The Spectator:
As the fighters of the Islamic State drive from village to captured village in their looted humvees, they criss-cross what in ancient times was a veritable womb of gods. For millennia, the Fertile Crescent teemed with a bewildering variety of cults and religions. Back in the 3rd Christian century, a philosopher by the name of Bardaisan was so overwhelmed by the sheer array of beliefs to be found in Mesopotamia that he invoked it to disprove the doctrines of astrology. ‘It is not the stars that make people behave the way do but rather the diversity of their customs.’
Bardaisan himself was a one-man monument to Mesopotamian multiculturalism. A Jewish convert to Christianity, a Platonist fascinated by the wisdom of the Brahmins, an inhabitant of the border zone between the Roman East and the Iranian empire of the Parthians, he stood at the crossroads where antiquity’s most potent traditions met and intermingled. Just how far the process of blending rival faiths could be taken was best illustrated by a man born in Mesopotamia a few years before Bardaisan’s death: a soi-disant prophet called Mani. Brought up within a Christian sect that practised circumcision, held the Holy Spirit to be female, and prayed in the direction of Jerusalem, he fused elements of Christianity with Jewish and Zoroastrian teachings, while also claiming, just for good measure, to be the heir of the Buddha. Although Mani himself would end up executed by a Persian king, his followers were nothing daunted. Cells of Manichaeans were soon to be found from China to Carthage. Syncretic as their religion was, and global in its ambitions, Manichaeism was a classic Mesopotamian export of the age.