Yoga is not a religion. It’s better.
True Yoga (typically not of the hot/power/yogalates ilk) is an innately spiritual practice, a meditation or prayer in movement. It grew up intertwined with Hinduism and Buddhism. Religion involves ritualistic, organized worship of idols or deities as in Christianity, Judaism, Shamanism, Islam, forever and ever amen. Yoga has no requisite god.
Yoga originated about 6,000 years ago in ancient India. It shares similarities with Tao and other Eastern thought, but yoga is its own unique science. Mormons, Jews, Scientologists and athiests alike can freely practice yoga without risking damnation.
Many yoga teachers chant “OM” and other Sanskrit mantras in class. When I first started, chanting made me highly squirmy. I didn’t know what it meant or why I was supposed to join in. Now, after much study and practice, I love it. The syllable OM is the primordial sound of the universe before Earth’s creation. In other words, OM is AMEN is SHALOM is HARE KRISHNA is CHRIST is GOD is the Universe is Divine Spirit.
Individuals can be religious and/or spiritual. Religion sans spirituality is for show and completely useless. Spirituality sans religion is for people who may study multiple religions or doctrines but don’t subscribe to any single path.