Atheism has been around since theism, and in a sense, much longer before it though it wouldn’t have been referred to as atheism. As long as there have been people who have religion, there have also been people who reject that religion; there hasn’t been a time where one hundred percent of the population was the same religion. In a sense, there is no real cause for atheism; everyone is born an atheist. Many people find ways to fall away from atheism and into theism at first, rather than the other way around.
Why did people deny theism?
The better question, I suppose, would be: “Why did people deny theism?”. There are a variety of explanations for this. One would be that some people have no reason or inclination whatsoever to be a theist. Their worldview is completely consistent without religion, and they are content with that. Why would they try to fix something that isn’t broken? If a worldview works fine without the inclusion of God, then it is probably best not to try and superfluously add God into the worldview because it can only complicate things.
Some people were atheists simply because they didn’t need theism in their lives.
They weren’t necessarily against theism, but it was just added nonsense to them and they didn’t want to change their perfectly fine worldviews for no value. There were, however, people who were actually quite opposed to religion; people who didn’t just mind their own business when people were using religion to exploit others. These were the people who saw the corruption, bigotry, and violence that religion can lead to, and they weren’t just going to stand idly by. People like Friedrich Nietzsche were vehemently opposed to religion claiming such things as the death of God, and that
Christianity stunted the forward progress of mankind. He wasn’t just a passive atheist, his atheism was fueled by dismay and disgust with religion. Though I do not personally agree with this style of atheism, it is certainly a cause of atheism among many people.
My personal experiences, as well as my interactions with other atheists, lead me to believe that much of atheism today is caused by something more closely related to the former cause, though there are still hints of the latter. Many of my atheist friends and myself are atheists because of a combination of a few things: quite possibly the most important is that the religious stories and ideologies are neither appealing or very believable. I’ve heard biblical scholars, as well as scholars of other religions, try to explain some of these stories and they always seem like nothing more than old myths. It’s very difficult for me to imagine how people can put so much faith and devotion into things like this.
Another very important cause of my atheism is modern science.
I am not the person that says that science disproves religion; I don’t believe we currently have the tools to do that. I am simply a person who strongly believes that science makes religion irrelevant. There are many people who agree with this, and it is certainly a huge factor in the atheism of many people. Lastly, there are a large majority of people who are atheists because of the corruption of churches and religions around the world. I personally am not in this boat, but there are certainly many people who are. The problem of evil is certainly a strong philosophical idea in regards to atheism, and when religions themselves are the ones causing a lot of evil in the world, it’s hard not to harken back to the problem of evil.
As I mentioned earlier, there isn’t really a cause of atheism in the sense that there was some cause, and the effect was atheism. The only real cause that would fit in that equation would actually be theism because there can’t be a lack of theism without theism! This doesn’t make much sense though because people were technically atheists before there were theists, but I digress. The main point here is that there a plethora of “causes” for atheism, and there aren’t really any strong indications as to which was first or which was the most important. All one can do (ironically) is believe.