BG Chap 17 - What determines one's faith?
According to the degree of sattva (sattvānurūpaḥ), the faith of everyone becomes manifest. The greater the degree of sattva, the more pure the faith is. A person is indeed what his faith is. This faith corresponds to the nature of the internal organ, called antaḥkaraṇa. This internal organ refers to the subtle organ consisting of the mind, intelligence, false ego and memory (citta). Simply put, the faith is of three types according to the nature one has acquired. Though faith itself is a function of sattva guṇa, faith transforms into three types thru the three guṇas, because the soul in the material world possesses an internal organ, and its very nature is to hold the impressions of the three guṇas. The internal organ is filled with the three guṇas, and corresponding to that, the faith of all living beings appear. The faith of the internal organ predominated by sattva guṇa is sāttvika, by rajo guṇa is rājasic, and by tamo guṇa is tāmasic. Thus we find different types of faith in this world, and there are different types of religions due to different types of faith. The real principle of religious faith is situated in the mode of pure goodness, but because the heart is tainted we find different types of religious principles. Thus according to different types of faith, there are different kinds of worship.