The contents of the book are based upon the materials collected through extensive and careful research, for the preparation of a thesis for a higher degree for the Lancaster University. It deals with the conception of Hindu religion, its history and progress along with the gradual rationalization of the belief and practices with the time, since Rigveda and its effect on the caste system. Special attempt has been made to present many complex theological topics, in a simpler way for the easy understanding of the young generation, on whom the religion depends enormously, for its future growth and expansion. The vast amount of information has been accumulated here in a concise form to make it a useful reference book for the students of religious studies and sociology.