So glad you asked, this is one of my favorite questions.
Yoga is like Santa Claus. Santa Claus is pre-Christian, he figured prominently in Siberian Shamanism, and other early traditions as well. Christians seemed to like him, and they 'made him their own'. Today, we see that gift giving of Christmas, is practiced by Christians and non-Christians alike. It is universal, and promotes much good will and fellowship.
Just the same, Yoga is a collection of practices that is pre-Hindu, and Pre-Buddhist, pre-Taoist. It was designed primarily by hermit yogis (living in forrests and mountains) who were mostly interested in self-knowledge and enlightenment, rather than religion. Later, yoga was discovered by religious people who enjoyed the practices, finding that they helped foster religious experience. Many of these religions 'made yoga their own'.
At Main Line Yoga, you will find that there will be practices that were designed by all manners of wise people. There are Taoist Practices, There are Tibetan Buddhist Practices, Tantric Practices, Hindu Practices, Judeo-Christian Practices, and Athiest/Agnostic Practices. They have been chosen by the teacher for one particular reason. THEY WORK! These practices are like gravity, they do not require your belief. If you jump off the roof, you will fall to the ground, if practice yoga, your life will become awesome. Regardless of the house of worship you attend or the God(dess) that you worship. Awesome.
For More On Santa, please feel free to ask Daniel after class.