Yoga and Hinduism
Read David Swenson's reply:
One need not take any vows or profess allegiance to any specific God in order to practice yoga. Yoga is a spiritual path, but not a religious one. The practice of yoga is a philosophy or way of life, but not a religion.
There are many different ideas about the origins of yoga. You have posed one, but its true history is a mystery, since there is little in the way of written texts portraying its origins. For the most part, it was a verbal tradition handed down from teacher to student. There is no indication that it was ever part of an organized religion. The beauty of yoga is that one can maintain any religious belief and still use yoga to enhance his or her personal path. Regardless of what we may read about the history of yoga, the true proof resides within the applications and practice of yoga for each individual.
The goal of a yoga instructor is not to direct students toward any particular direction or faith but rather to encourage, inspire, and facilitate practice in order for students to take the benefits of the practice and apply them within the context of their unique paths. There is no need to attach a religious label to yoga anymore than there is a need to attach a religious label to penicillin. Regardless of one's religious affiliation, the medication will do its work without bias.
David Swenson made his first trip to Mysore in 1977, learning the full Ashtanga system as originally taught by Sri K. Pattabhi Jois. He is one of the world's foremost instructors of Ashtanga Yoga and has produced numerous videos and DVDs. He is the author of the book Ashtanga Yoga: The Practice Manual.