Was the religion in ancient Mesopotamia Greek?
No, they had their own pantheon, each city having its own gods. Greek influence arrived with Alexander in the late 4th Century BCE, however the Greek pantheon did not prevail. Of course, the various gods were simply parallels of the same functionary, and recognised by various peoples as such eg the high god was Jupiter (Roman) = Zeus (Greek) = Yahweh (Jewish) = Amon (Egyptian) = Enlil (Mesopotamian) = Ahura Mazda (Persian). No one was particularly fussed about it. When Pompey captured Jerusalem, he automatically went to the temple and sacrificed to Yahweh (Jupiter). Religious distinctions (and wars) are a modern invention of the exclusivist children of Yahweh (Judaism, Christianity and Islam).
