Conventional wisdom of many on the progressive side of politics and social change is that religion, particularly Christianity, is a key source of our culture’s problems if not evil in general. John Lennon’s classic song "Imagine" conjures a utopian world that would be free of this supposed source of division and strife. Many people more on the conservative side of things do not share that concern about the Christian faith and its practice, but see Islam in that same sort of negative light. My take is that neither (nor religion in general) is a source of hate, war and oppression, actually came into being to promote love and humanistic ideals, but have been manipulated as tools of a much older ideology of domination and "us and them" thinking that some would call "Patriarchy".
Now I am no more or less a half-baked amateur religious historian than many others, but I come to this opinion after a fair amount of study and thought, including reading Riane Eisler’s The Chalice and the Blade and Sacred Pleasures, Karen Armstrong’s A History of God, The Battle for God and Holy War, Lawrence and Nancy Goldstone’s Out of the Flames, plus other tracts on history and how it has interacted with religious theology. So take my theorem for what it’s worth and with a grain (or even a pillar...*g*) of salt of course, but here goes...
My working theory is based around the premise that the Axial Age (that thousand years between 800 BCE and 200 CE) as coined by 20th Century German philosopher Karl Jaspers, and described by him (per Wikipedia) as in fact "an interregnum between two ages of great empire, a pause for liberty, a deep breath bringing the most lucid consciousness". Without any apparent connection or cross-pollenization, great philosophers emerged and their philosophies were codified in religious thought and practice that still play a key role in contemporary societies and cultures throughout the world. During this period we see the emergence of philosophers like Buddha, Confucius, Jesus and Plato and an array of religions – Judaism, Hinduism, Christianity, Buddhism, Confucianism, and Zoroastrianism – that two millennia later have over a billion adherents.
Prior to this age, there is plenty of archeological and written historical evidence of domination, violence and hate reflected in archeological digs from that period along with other historical records. Most noted in standard ancient history textbooks are the various Babylonian, Assyrian and other empires that arose in the Fertile Crescent (in modern-day Iraq) and conquered neighboring areas plus similar militaristic practices by smaller and more nomadic tribes on the fringes of the more settled fertile valleys around the Mediterranean Sea. Eisler in particular (based on the archeological work of Marija Gimbutas and others) paints a scary picture of an age of unmitigated violence and domination, the various dominator cultures celebrating the strength of warlords (whether human or deity) and the destructive power of "the blade".
But we humans are ever evolving, and maybe the great Golden Rule and "love thy fellow man" (if not women) thinkers of the Axial Age were the "progressive" activists of their own era trying to inspire the best in the human character rather than the worst, advocating codes of practice like the Ten Commandments or Confucian teaching, in an attempt to mitigate the prevailing hierarchical "command and control" by any means necessary prevailing conventional wisdom of the period. Certainly if one looks at the surviving tales of the actions and words of the Jewish prophets of this period, Jesus or Buddha, there is no hint of the "us and them" justification of violence or conversion at the point of a sword that characterized certainly the organized practice of the Christian religion with its Crusades and Inquisitions during the Middle Ages.
Focusing particularly on Western history (which I am more familiar with) it was an emperor like Constantine I who was not born a Christian but essentially adopted and molded the religion as a tool for building and maintaining his Roman/Byzantine empire. It was perhaps emblematic of the end of Jaspers’ Axial Age and the use of its progressive thought for a perhaps far less noble purpose of control and domination.
In 325 CE Constantine convened the Council of Nicaea, a gathering of Christian bishops within his empire charged with coming to consensus on a version of Christian thought that would become his state religion. One of the thorny questions they wrestled with was whether Jesus was born human or an aspect of God. This was more than an esoteric theological question. If Jesus were a human who achieved godhood then would not other people within Constantine’s control aspire to likewise challenge secular authority as the Gospels told that Jesus did? But if Jesus was born an aspect of God (the "son" of the "father, son and holy spirit") then his perfection was unattainable by muggle humans who, in all things, needed to listen to their more enlightened authority figures.
Islam, though founded four centuries after the Axial Age, grew out the same innovative and humanistic ideas that spawned the other Abrahamic religions, repackaged in the Arabic language for the peoples of that region. In the early centuries of its spread and influence it encouraged great scientific thinking, while Christian Europe was plunged in its Dark Ages. Later the religion, like Christianity before it, would become be co-opted as a tool of secular empire building and control and would develop its own dysfunctional hierarchies to exercise control.
In the same vein, the Huns, Goth, Vandals and other militaristic tribes that invaded, conquered in settled in the areas that would eventually become modern Europe adopted Christianity and torqued its Golden Rule turning a loving Jesus into their metaphorical warlord justifying later Medieval massacres of Jews and repeated bloody Crusades against the equally infidel Muslims. Though still bearing its founder’s pseudonym (Christ-ianity) this was no longer any ethical or spiritual practice of "turn the other cheek" that that founder could possibly recognize or endorse.
In my take this was pure unadulterated Patriarchy, power-over domination and control being exercised by male warlords using this religion to give them supposed justification from the Father God in the sky for very unethical behavior. The warlord’s torque of the Golden Rule was to say that I do the bidding of the Father in the sky, so my serfs and vassals in turn must do mine. If the emerging infrastructure of Christianity had not been available, these tribal leaders would have just as easily built a justification for their absolute rule around the Olympian, Norse or other deities, anything that would give them the bonafides of themselves answering to a higher power.
Move the historical time line forward to the Protestant Reformation that launched the Modern Era. A Papal hierarchy controlled Rome, the Roman Church, and its lucrative "franchising" of cardinals and bishops throughout Europe, using that funding source for wars and orgies and other very worldly indulgences of the rich and powerful. In my mind this was patriarchal hierarchy building, masquerading as the religion of Jesus and his disciples. This corruption was called out as anything but Christian by the monk Lutherwho perhaps naively thought this was still the "meek shall inherit the earth" ideology that the carpenter from Nazareth had originally called out.
This reinvigorated "reformed" Christianity, both Protestant and Catholic, looks to have played a positive role in challenging dogmatic thinking generally and perhaps helping clear the path for a flowering of scientific and other more secular thought, an age of exploration, free enterprise and budding egalitarianism. The dark side of this new era was that exploration led to exploitation of the indigenous people seen as inferior and industrial enterprise led in many cases to turning autonomous individuals into interchangeable cogs in the mechanization of society. I see the whole Calvinist theological concept of "election" torqued by the industrial barons (the modern equivalents to the ancient and feudal warlords) into a religious justification for a return to secular domination and control.
Perhaps I am trying to paint with too epic a brush for an effective four-page essay. Getting back to what I started to try to say here, I think our progressive cause is poorly served by painting religion as the antagonist in our struggle for a more humanistic and caring society. I would put forward that our main antagonist instead is Patriarchy, the exaltation of the stern, controlling father figure and male-centric hierarchical thinking. This ancient worldview that held perhaps unmitigated sway before the Axial Age continues to be a path of least resistance for people who wield power, whether justified at the moment in religious or secular ideology.
Though I am not a believer in god myself (though I am comfortable around believers) and I try to rationalize deities as a metaphor for some deeper level of transcending mystery that we can not fully grasp. But I would not be surprised, like in the 1960s with the Civil Rights movement, if inspiration for progressive thought, action and evolution is yet to come from new or reinvigorated religious doctrines. This, as we continue to challenge what I see as the real culprit, this ancient ideology of the power-over hierarchy built aroung the stern father figure. Until we acknowledge that true source that stands in the way of our progressive principles and efforts, I believe we will be just tilting at windmills.