Have you heard the one about the rabbi, a priest, and an atheist walking into a yoga studio? I have. It's no joke, and happens all of the time. Yoga is a practice of many things—movement, balance, observation, breath— but yoga is not a religion.
Anyone can practice yoga. In one class, you will commonly find people of all beliefs—Jews, Catholics, Muslims, Buddhists, Hindus, Agnostics—practicing next to each other. Like many other experiences, yoga is very unique to the individual as much as it is to the community practicing together.
Often, classes can start with chanting and/or some talking about yogic philosophy. Take it or leave it. You shouldn’t feel forced to do anything you aren’t comfortable doing. Yoga is a simple action to which people attach their own meaning. Before you make any decisions, try it first and make an informed decision from personal experience for yourself.
So, yoga isn't a religion -- but it is a life-changing practice that might just make you a better and healthier person.