There's a widespread confusion between religion and theism. Sociologically, religion could be understood as a collective practice of an ideology, and the ideology can be secular. Cults bind smaller groups, religions large populations or civilizations. The key thing is that the ideology and practice should be fundamental to your identity; otherwise, the practice could be just a hobby or a performance. Religions have existential gravitas for their members. The lifestyle has to feel natural, self-evident, and profound.