Nanak (1469-1538 A.D.) was the son of a Hindu from the Kshatriya (ruler, warrior) caste in northern India. As a boy, he was greatly influenced by itinerant holy men, some of whom represented the Bhakti school of Hinduism and others the Sufi form of Islam.
Nanak believed in a supreme being, but concluded that all religions were using different names for the one true God whom he called "Sat Nam" (True Name).
As he grew into adulthood, Nanak attempted to harmonize Hinduism together with Islam, thus producing a new religion known as Sikhism. The word Sikh is Hindu for "disciple."
Nanak wanted to rid religion of rituals, ceremonies and pilgrimages. He denounced the Hindu practices of idol worship, caste, sacrifices and infanticide yet adhered to the Hindu ideas of karma and transmigration.
Nanak taught that the means to salvation was acquired both by grace of Sat Nam, and by works (righteous living is required).
After attaining salvation, an individual is believed to be absorbed into God. The Sikh concept of God is monotheistic in form, but it is so mystical and abstract that it is ultimately pantheistic.
The will of the divine guru is made through special human gurus of which Nanak was the first, later followed by nine other gurus. The fifth, Guru Arjun (1581-1606 A.D.) compiled the basic scripture, Adi Granth ("The Original Book") which were poems, prayers and sayings of the first four gurus and other writers. Guru Arjun was also responsible for turning Sikhism into a social and political organization as well as a religious movement.
Within 60 years after his death, Nanak was deified by his followers who said "Guru Nanak is God, the Supreme Brahma," (Gurdas 13:25).
After the death of the tenth and final guru, Guru Gobind Singh (1675-1708 A.D.), loyalty shifted from that of the personal guru to that of the Granth Sahib ("Lord Book") when he declared that the scriptures would thereafter be the guru of Sikhism. A copy occupies a throne under a jeweled canopy at the central shrine, the Golden Temple of Amritsar.
Although they claim to spurn idolatry, the Guru Granth Sahib is treated as though it were a person, is worshiped as an idol and is considered as absolute authority. It is the most difficult sacred book to read (it is written with a special script in six languages) thus very few Sikhs can read it at all.
Sikhism today has approximately six to eight million adherents, most of whom live in their ancestral home of Punjab, India.