The main reason that I quit antitheism was that I slowly realized that religion is only an excuse rather than a cause of oppression. The Crusaders did not simply read the Bible and immediately go out on a rampage. That would almost be like saying that violent video games make innocent people become violent themselves. Underneath the façade of religion are causes far more complex than that.
In the Crusaders’ case, the European ruling classes were interested in grabbing land and other resources from Palestine and the inhabitants therein and thereabout. The situation was similar for chattel slavery and serfdom: they merely used religion as an excuse. It was not the cause (the cause in this case originating in upper‐class dominance). There were far more examples of religiously justified oppression than those, but I think that you understand what I mean: the causes go deeper than what the surface suggests.
More recently, heterosexists and cissexists can distract us from their attitudes by pointing to scripture, but careful hermeneutics and human reason (of which, I’m sure monotheists would agree, the Almighty created) suggest that scripture is not the problem. It is the neopatriarchal attitude that is the problem, and mistaking scripture for the source—as if the scripture’s own stances came ex nihilo—is a classic case of confusing cause and effect. Religions are cultural phenomena; they are subordinate to culture, and cultures mutate regularly. That is why I used to liken religions to clay.
Even if our oppressors never had religion, they still could have appealed to pseudoscience, and most already do. Quite a few irreligious men are misogynists who’ll justify their oppression by claiming that women were genetically programmed to be caretakers or whatever. In fact, one could argue that the pseudoscientific excuse is more dangerous than the religious one because respect for science is almost universal whereas religions and spiritualities are very culturally specific.
Lastly, lower‐class monotheists can and have rebelled against their oppressors before. I believe that quite a few poor peasants during the Protestant Reformation were monotheists and yet they rebelled against their masters anyway. Religion is not a perfect tool for mind control; lower‐class monotheists can be just as revolutionary as lower‐class atheists, and upper‐class atheists can be just as troublesome as upper‐class monotheists.
That is why I gave up on antitheism: its explanatory power is woefully inadequate. There were a few other reasons, but the ones that I described above were the most important.
One of the minor reasons that I resigned myself from antitheism was that I was becoming pretty disgusted with how other antitheists were misbehaving. For example, a dozen years ago I watched a video of some white guy destroying a Qurʻan with a chainsaw and then drinking the shreds in a milkshake. (???)
More infamously, dozens of artists would make intentionally provocative and insulting depictions of an Abrahamic prophet, dirty Qurʻans or images of a prophet, intentionally destroy undamaged Qurʻans, and so forth… I found those actions and depictions to be very immature and nauseating in their own right even though I still disliked Islam, and that they portrayed their immaturity as being for a good cause—‘free speech’—was just embarrassingly pompous and melodramatic.
When I read about how the Crusaders treated Jewish artifacts, I thought back to those times of antitheists and other Islam‐haters behaving so immaturely.
Lastly, I think that for many of us in the lower classes, religion and spirituality are simply ways in which we cope with trauma. They may crude ways of handling a serious problem, but sometimes they’re the best that we can afford in a hyperindividualist, largely uncaring society with inadequate mental healthcare. Taking away a poor person’s faith wouldn’t fix anything.
Basically the point of Marx:
Religious suffering is, at one and the same time, the expression of real suffering and a protest against real suffering. Religion is the sigh of the oppressed creature, the heart of a heartless world, and the soul of soulless conditions. It is the opium of the people.
The abolition of religion as the illusory happiness of the people is the demand for their real happiness. To call on them to give up their illusions about their condition is to call on them to give up a condition that requires illusions. The criticism of religion is, therefore, in embryo, the criticism of that vale of tears of which religion is the halo.
Criticism has plucked the imaginary flowers on the chain not in order that man shall continue to bear that chain without fantasy or consolation, but so that he shall throw off the chain and pluck the living flower. The criticism of religion disillusions man, so that he will think, act, and fashion his reality like a man who has discarded his illusions and regained his senses, so that he will move around himself as his own true Sun. Religion is only the illusory Sun which revolves around man as long as he does not revolve around himself.The Crusaders did not simply read the Bible and immediately go out on a rampage. That would almost be like saying that violent video games make innocent people become violent themselves.
There's a big difference between video games and religion (except in Dark Souls, of course), especially religion as practiced during the Crudades. Religion has true believers in a way other cultural practices rarely do.
Your overall point about material reasons largely driving the type of oppression/aggression we attribute to religion is a good one, but it's a bit overstated. People make religious decisions that harm their material interests all the time -- look at tithing, or those evangelical "send me money for your sins" TV shows.
But that's weaponised religion, just like the crusades. It uses people's belief system to exploit them.
Religion is a means, not an end. It can be used for extreme feats of generosity, or resistance, for example. And it can be used to oppress and empoverish.
How it's used depends exclusively on material conditions for whom is in control of what the belief system is used for, for which there's extreme variety from the micro to the macro scale.
Religion is the opium of the people.
-Karl Marx
Opium is a wonderful in the case of a person dying or in great pain, but in other circumstances, can be quite harmful. Contemplating religious concepts can be helpful for getting through extremely trying times. It can provide comfort in the face of the unknown. This allows religion, like corrupted science, to be twisted into something used to support atrocities. Sadly because some people seek truth through religion, and rely on religion for their morality, it is easily twisted into a weapon of war. It is similar to the way opium was turned into a weapon of war against China in the mid 19th century.
I like to think of religion as a pain medication for the spirit. Even in a wholly just society, people die. Their loved ones will feel that pain, and religion can provide some relief.
It needs to take a back seat to historical and dialectical materialism, to the meeting of people's needs. It's not something you can really just debate or logic away nor is it something you can simply crush by outlawing or cracking down on. It's a historical process just as the rise of monotheistic religions was.
So yes it's a liberal or reactionary tendency if you're just saying "religion causes bigotry, without it we'll have a better world". Without Marxism atheism is nothing particularly progressive, religion has long been very helpful in upholding reactionary thinking and systems but not strictly necessary as many have been upheld by people who gave it little credit or thought.
I wouldn't call myself that these days either because of how many reactionaries the space has and because being a Marxist-Leninist is frankly more important and more accurate a description than simply being anti something.
However a point I would make (which has already been made) no one except those severely mentally ill believes that Halo or Call of Duty is real or that not obeying it or a message they think they see in the Matrix will result in them being eternally tortured and injured as opposed to granted eternal bliss. No one thinks those are instructions or commands from an all knowing, all good, benevolent all powerful entity which will save or damn them based off their choices to adhere or not to those messages. Nor are their institutions or systems built around adhering to those messages that date back centuries, nor places where people steeped in the knowledge of the lore of these things study before going out to lecture to the masses about it, nor volumes of works and thousands of lifetimes of humans thinking on it dedicated to it. And on and on.
Warning: Long rambling
spoiler
Religion is REAL for believers. They really believe it. It's hard for many who didn't grow up in fundamentalist households to understand but it's not something they just adopt on Sundays and then entirely leaves their lives. Many of them live in terror and joy and real anger and fear over it. The penalties are impossibly high, the rewards are impossibly high. Compared to what we can offer our punishments and rewards to them are as nothing for many (not all but enough). Yes they're often inconsistent, fraught with problems adhering to it. Contradictions. Such is humanity.
Yes these believers often make excuses, sin, and pick and choose but it provides a hard backstop for reactionary, backwards, frankly oppressive beliefs such as homosexuality. It codified as eternal, unchangeable in holy writ things like the second class nature of women, the impermissibility of being gay. It codified old/ancient things like patriarchy and homophobia with various original root causes. And having been around true believers I can say if we invented a way to extend human life to 300 years you would not convince at least 30% of these people to change their ways, to stop being bigots in a hundred years if you gave them a Star Trek society free from want. Not without coercive institutionalized re-education methods that are expensive, time-intensive and not 100% effect. Yes to some extent these people are whipped up by the forces of capital seeking to divide the working class, to scapegoat, etc but it's not like they pulled out of a hat in the 1960s that being gay is bad (they did pull out of a hat that abortion is murder and theologically impermissible however but that stems out of the harder backstopped beliefs of women as property, as beneath men and the need to control women and their sexuality, that men should be in charge under a male god-head so even if they don't really believe it, it's still true to their cause to claim to believe it to use it in such a way as to achieve putting women where they belong according to their beliefs).
These are beliefs and practices that have been held for centuries, a thousand years. It's just that for most of those thousand years such things were taken by those who lived in the lands held by these believers as givens, they weren't argued, they weren't seen as contradictory to any larger culture or superstructure. We now have a situation where that isn't true, where there have been women's rights movements, LGTBQ+ rights movements which have pushed back and won gains.
But it isn't that all religious believers who still seek the outlawing of gays or the oppression of women even necessarily wish this, yes many do but I've met those who squirm and seem uncomfortable about it, who otherwise are not entirely horrible people, who give to charity, who are to those around them at least kind, but basically just shrug and at the end say god is mysterious and they must obey, they don't want to oppress these people, they wish there was a middle ground they say but the commands of their god are clear and in this they are more correct than the liberal reformers who attempt to reform a holy text (The Bible) which cannot be altered or reformed according to its own instructions. These reactionary tendencies thus will always have the high-ground and will always remain a threat.
Look, if Marx had written in multiple works that women are bad actually and here's some pseudo-scientific misogyny and oh you need to keep them in check beneath you that there would be an ever-present, ever-returning tendency of Marxists who would seek to uphold this despite the attempts of reformers later on and despite the fact that theory is not holy writ and scripture and not supposed to be divine, infallible, or perfect nor read as commands to be carried out unthinkingly and robotically. I mean we've still issues with Maoist ultras, Trots, etc after all the disproving of that and many of them religiously cite theory and you can and should beat them over the head that it's not a religious text and nowhere does it say that in itself unlike many holy books.
Religion is part of the superstructure but it's a part that's partially frozen that dates back to ancient times and the whims of the ruling class then which was a propertied class, which was the debt-owning class. And it has stayed relevant because throughout the last thousand years Christianity has been very useful as we've transitioned into a capitalist society. The slave mentality that it encourages in believers, for slaves to obey their masters is anti-revolutionary, it is for lying down, for being trodden upon, for accepting an unfair and unequal system because anything else would be an abomination, a lie of a heaven on earth that cannot exist because earth is fallen as is man.