Santals are one of the most dominant tribes in India. They are the third largest tribal community in India after Bhil and Gond tribes. In West Bengal, among the listed forty scheduled tribal communities, the Santals are the largest tribal community. They have been described as the “most integrated and possibly the most resilient tribe in eastern India”. The name of the traditional religion of Santals is ‘Sarna’ or ‘Sari’ dharma. Among the Santal, the religion is closely chained to every facet of life. Santal traditional religion is a mighty belief in strengthening the social harmony of the people. Santals have different gods and they call them by different names, but they don’t have the statue of the Gods. They have their own methods of prayer. According to Tylor, religion is the “belief in spiritual being”. Troisi analyses the Santal religion as man’s relation to supernatural powers and the various organized systems of belief and worship in which these relations have been glorified. The relationship between a Santal and supernatural beings and powers that one cannot completely able to interpret the Santal social structure unless one goes through and feels their religious universe. This paper focuses on their beliefs and perceptions of God, benevolent, malevolent spirits and the religious practices followed by them which are entangled in their cognitive process including the effect of Hinduism and Christianity on their traditional religious beliefs, rituals and practices.