First Sikh Guru
He taught that human life is a very precious opportunity to meet the creator, God, through absolute love and devotion to him. He taught that the sins of lust, anger, greed, attachment to worldly things, and arrogance or pride take us away from God. Guru Nanak always taught by example and through his own humility, love and devotion to God he taught how human beings should live.
At the age of five he was sent to school. His teacher Gopal Das wrote the letters of the alphabet on a slate and Guru Nanak asked what each letter meant. The teacher was amused and pointed out that the letters by themselves did not mean anything. Gopal Das then turned the question around and asked Guru Nanak what he thought the letters meant. Guru Nanak spontaneously went through the alphabet and used each letter as the start of a verse of poetry in praise of God. That hymn is present and unchanged in Guru Granth Sahib. The teacher was amazed at the beauty and truth of his words and at his understanding of God and command of language without ever having been taught. He realised at once that Guru Nanak was no ordinary child, but a divine messenger of God. According to Hindu Custom, when a child reaches the age of eleven he is given a sacred thread to wear.
When Guru Nanak was eleven, a great ceremony was prepared for him to receive the thread. However, to everyone's surprise, the Guru declined to wear it, saying that a thread can break and therefore cannot even accompany a man through life. He said, 'I want that sacred thread which after the death of a man accompanies his soul to the next world'. The priest asked what kind of sacred thread he had in mind? Guru Nanak replied: 'Make kindness the material, and spin the thread of contentment. Tie knots of truth and virtue. These qualities in a person are the real sacred thread'. Guru Nanak spoke these words in beautiful poetry and this hymn is also in the Guru Granth Sahib.
Throughout his life, Guru Nanak continued to spread God's message, travelling across many countries for more than twenty years. He taught that all are equal before God and that love for God also means caring for God's creation. He opened people's eyes to the falseness of rituals, idol worship, caste prejudice, and oppression (including oppression of women). He taught that only with unquestioning devotion can one reach God, regardless of caste, race, nationality or religion.