I will point out that while most religions believe in some sort of higher power (whether at least one deity, cosmic force(s), spiritual web, etc.) there are a few which don’t. One can argue that the ones which don’t are just pseudo-religious philosophies, but that’s rather unfair, and not how most people use words. Other factors common to religions are dogma and sacred texts, which do exist in the non-higher-power religions.
Do atheists believe in higher power(s)? Some Christians would argue “evolution”, but there’s a difference between “believing something is real” and “believing that something offers spiritual and/or moral guidance”. Others might argue that atheists worship themselves as a higher power (as if we were Ascended Masters or something), but that’s coming from a place of “God guides your life, so if you try to create your own destiny you’re replacing God with your own ego” which is not something even the majority of Christians believe.
Do atheists have dogmas? One can reasonably argue that the belief that religion itself is dangerous and should be stamped out, which is the basis of the subset of atheism known as antitheism, is a dogma, but that’s not something common to atheism as a whole.
Do atheists have sacred texts? Some Christians might claim the works of Charles Darwin (or occasionally, Richard Dawkins) are “sacred texts” for atheists, mostly because of evolution. While it’s true that evolution does have some limited explanatory insight to human behavior and morality, most atheists haven’t read them, and virtually no one uses them as a guideline of any sort. And neither Darwin nor Dawkins are the end-all or be-all of evolution - science marches on, rather than being frozen in time like religion typically is.
Now it’s still very reasonable to put “atheist” in a list of religious identities, in the same way that “N/A” and “Prefer not to say” are usually options in well-crafted surveys, simply because a lot of non-religious people do use the term “atheist” to describe their non-religiousness, even though atheism isn’t meaningfully a religion… even if doing so confuses fundies as a result.
