The dictionary definition of religion includes : a cause, principle, or system of beliefs held to with ardor and faith.

TST has a robust set of tenets that lays out their moral code and belief system, as well as community and ceremony.

As far as other religions that are not based in supernatural deities, look up non-theistic religions and you’ll find flavors of Buddhism, Christianity, Hinduism, and Jainism that all follow moral teachings of the religion without acknowledgment of the supernatural deity.

The supernatural is just one explanation for ‘why’ you should follow the religion, but the religion is more about the community, system of moral codes, and ceremony, in my opinion.

I had this debate with a southern baptist one time and came to realize that we had very different reasons to follow or not follow a religion. He was not “doing whatever he wanted, like raping and murdering” because he had the fear of god and didn’t want to spend eternity in hell. I don’t do those things because I have empathy for others and my moral code makes me treat others the way I’d like to be treated. If belief in the supernatural helps you be a good person, please continue in your flavor of religious practice. But understand that other people may not need the same supernatural incentives to follow their religious beliefs and that doesn’t mean their beliefs are any less important to them than yours are to you.