The nature of the work ethic of a society may significantly shape the character of its economic development. It is argued that the cult of Vishnu and its associated work ethic have played a notable role in the economic development of India during the past 2000 years or so. The cult of Vishnu appears to be a fusion of the cults of the Vedic God Vishnu, the cosmological deity Narayana, Vasudeva of the Vrishnis who promoted the Bhagvata cult, and the cowherd boy Krishna. Vishnu that has emerged as a fusion of these cults, and elaborated in his avatars or incarnations, appears to have a pragmatic, “business friendly”, resourceful manager orientation, who may preach high spirituality but in practice uses pragmatic means to achieve ends. The Bhagavada Gita, the centerpiece of Vaishnava spiritual philosophy, while excoriating greed, provides a powerful structure of the work ethic that upholds the necessity of effort and legitimises every manner of mundane pursuit including commerce provided it is pursued with detachment and is dedicated to God. This work ethic bears some striking similarities to the Protestant Ethic described by Weber and suggested by him to be a major impetus to the rise of capitalism in the West. The emergent cult of Vishnu may have originated in coastal trading communities of southern and western India, in view of the many marine associations of Vishnu, and then have spread to the rest of India. It may also have been influenced by contacts with West Asian civilizations. Several hypotheses are stated that follow from the main hypothesis of the cult of Vishnu influencing India's economic development.