No, yoga isn't a religion. Hindu is. However, yoga provides a framework to help you live a little more in line with your religion. American yoga teachers might mention the Yoga Sutras in their classes, and the sutras themselves give you tools how to reach union with the object of your desire. It's similar to what St. Teresa of Avila talks about in Interior Castle. The aim in yoga (and contemplation) is union or oneness. It's up to you with whom you want to be unified.
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