His birth is celebrated world-wide on Kartik Puranmashi, the full-moon day which falls on different dates each year in the month of Katak, October–November. He set up a unique spiritual, social, and political platform based on equality, fraternal love, goodness, and virtue. It is part of Sikh religious belief that the spirit of Guru Nanak's sanctity, divinity and religious authority descended upon each of the nine subsequent Gurus when the Guruship was devolved on to them.