BG Chap 17 - The nature of faith that goes against the scriptures
The demoniac people, who are filled with ostentation and pride, undergo extreme austerities contrary to the scriptures, to attain their sense objects. Without any discriminating scriptural knowledge, they afflict the elements in the body and also the Supersoul residing in the body. They perform austerities, which give pain to others, according to their own scriptures, which are contrary to the Vedas. They are endowed with ostentation and pride, because without those two, they could not transgress the rules of scripture. They also have desire for eternal youth, eternal life, kingdom and such things, attachment to their particular austerity, and ability to perform the austerity. Endowed with obstinacy, they make the combination of elements, which are the basic components of the body, wither away by means of such things as useless fasting. They also lose the mercy of the Lord by offending Him. Those in the mode of passion and ignorance would more likely be engaged in the activities mentioned here. They can still have their demoniac natures destroyed by the very strong mercy of the followers of Vedic principles, by developing faith in the scriptures. Those who worship the devas, by attaining the mercy of those fixed in Vedic principles, very easily begin to follow the rules of scripture because of being situated in the mode of goodness. They are least likely to indulge in the activities of demons mentioned here.