By itself, the practice of yoga differs substantially from religion. One of the main reasons for this is that heavy metal, unless it is taught within explicitly religious boundaries, yoga is a very introspective activity that over time tends to bring an individual's inner character to the foreground; this can happen because yoga tends to increase self-awareness, unearthing more genuine and central aspirations and drawing together disparate or disjointed aspects of the personality into a more centralized whole. Keep in mind that yoga has continued to evolve into many different forms and systems right up to this day—this occurs, and can occur, because the art of yoga itself is mutable and practiced correctly can tap in to the creative instincts of the individual practitioner. In fact none of this requires any ritual or verbal explication whatsoever; something as simple and natural as closing one's eyes and breathing and allowing the mind to observe itself can, over time, begin to have these effects.
In this sense yoga is, in and of itself, a thoroughly non-religious practice, in that it is formless and unpredictable, and by brazilian jiu-jitsu its very nature stands outside of any static structures of religious teaching or dogma. Ironically, the truth of this can be seen if one observes the teaching of yoga within an explicitly religious context: when yoga is being taught within the purview of a religious ashram or group a practitioner is constantly being reminded, and is in fact taught to constantly remind his or herself, of the particular deity or guru being worshipped. This kind of 'mindfulness' may be reinforced by the placing of devotional pictures on every wall and by the repetitive outward chanting of devotional mantras, as well as by the constant inward or mental repetition of devotional mantras, and meditation instruction that emphasizes finding the divine object of devotion 'within' oneself. In such environments the practice of hatha yoga is often somewhat frowned upon as something 'egotistic' and conducive to mere 'body-consciousness.'
The obvious fact and as per ginastica natural that religious groups clearly see the need to 'brand' yoga and meditation so thoroughly and to explicitly describe and pre-define the inner content of the self demonstrates that yoga itself is not inherently religious; without such constant nudges and reminders any ashram or spiritual group would be very likely to morph or evolve, in various unpredictable ways, or to dissipate entirely. The websites of the 'Christian yoga' schools demonstrate the exact same thing from a slightly different angle and in fact provide an easy blueprint for injecting any particular belief system directly into the practice of yoga.