The term 'Guru' in Sikhism is not used for a teacher or a guide or an expert or even a human body. The word Guru is composed of two terms-

GU- means darkness and
RU- means Light.

In Sikhism the word 'Guru' is, thus, defined as the Light that dispels all darkness, and that is called JOT (Divine Light). Guru Nanak was, therefore, the EMBODIMENT of Divine Light:

'Gur Nanak Dev Govind roop.' (Basant Mohalla 5, p-1192, Guru Granth Sahib)
'Guru Nanak is embodiment of the Light of God.' (Translation of the above)

The Guru in Sikhism is a perfect Prophet or Messenger of God in whom the Light of God shines fully, visibly and completely. Guru is in union with Divine. Thus he ushers the devotees, the seekers of Truth into a spiritual birth. Through him the Glory of the Lord is transmitted to humanity. On account of his Divine prerogatives, the Guru, though human in form, is Divine in Spirit.

Literally Guru Nanak's body was a platform from which God Himself spoke and delivered His message- Gurbani (Divine Word). God manifested Himself through Guru Nanak:

'Gur meh aap samoai sabad vartaya.' (Var Malar ki Mohalla 1, p-1279)
'In the true Guru (Nanak) He installed His Own Spirit Through him, God speaketh Himself.' (Translation of the above)

In another place in Gurbani it is said:

'Gur meh aap rakhaya kartare.' (Maru Mohalla 1(15), p-1024)
'In the body of Guru (Nanak) God revealeth Himself.' (Translation of the above)

God is in the Guru and Guru is in God. Though God is everywhere and in everybody but His traits are illuminated through the Guru. The Jot (Divine Light) that enshrined Guru Nanak's body and the Primal Jot of God are, therefore, one and the same:

'Gur Nanak Nanak har soai.' (Gaund Mohalla 5, p-865)
'O Nanak, Jot of Nanak and God are one.' (Translation of the above)

Again the Janamsakhis (biographies) reveal that God spoke to Guru Nanak and said:

'Mei aad parmeshar aur tu gur parmeshar.'
'I am the Primal God and thou art Guru God.'

Guru Nanak never claimed that only his disciples or devotees could get salvation or go to heaven. Since he was the embodiment of Divine Light, and as the Divine Light does not belong to any particular sect or religion, so he stood guarantee for the entire humanity, and said,"Whosoever meditates upon One God, the Formless, will get salvation."

'Jo jo japai so hoi punit Bhagat bhai lavai man hit.' (Gauri Sukhmani Mohalla 5, p-290)
'He shall become pure whosoever repeateth His Name With devotion, affection and heartfelt love.' (Translation of the above)

When Guru Nanak conferred Guruship on Bhai Lehna (later called Guru Angad), the JOT was passed on and Guru Angad too became the embodiment of Divine Light. In the same way all the nine Gurus were the embodiments of Gur Nanak Jot. The tenth Master, Guru Gobind Singh then conferred the Guruship on Guru Granth Sahib (Holy Scripture), which too became the embodiment of Divine Light. Gur Nanak JOT is, therefore, enshrined and preserved in Guru Granth Sahib (it is no longer the Adi Granth, but only the Guru Granth), and it is the Living Guru for ever. For the Sikhs, the Guru Granth is the manifestation of the Guru's Spirit and through it, Guru Nanak lives on in the Sikh Faith.

Sikhism endeavors to uplift the human soul from the shackles of Maya (materialism). It aims at a virtuous life which leads to the ultimate realization of a state of Eternal Bliss. The objective of Guru Nanak's Guruship was to give instructions in the True Name, to save humanity from immersing in the ocean of distress and misery arising out of worldly life, and to blend the human souls with their Creator, thus, emancipating them from the cycle of transmigration breaking all barriers and bonds of sufferings. This is the essential character of Sikh faith.

The law of Karma or fatalism is repugnant to Sikh Religion as it does not reconcile with the merciful trait of the Almighty Lord. There is no such thing in Sikhism as eternal damnation or an everlasting pit of fire created by the revengeful God. Guru's grace erases the blot of thousands of evil deeds of the past and the present. It is also the savior of the future. Meditation on Nam burns countless sins. Singing the glory of the Lord through the Divine Word, can redeem a repentant sinner and, thus, doctrine of Karma ceases to operate. Such is the splendor of Guru Nanak's doctrine of God's Grace and Compassion.

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FN-1: - Gur Nanak Jot is not a human body but the Devine Light