Sikhs honor the Sri Guru Granth Sahib because the Guru is like a King in a divine court, in the court of God. The Guru represents all the beautiful values and Truth in life.
It is the actual words spoken by the Gurus and other saints and bards during divine communion with God. That is why Sikhs honor the Sri Guru Granth Sahib as the actual physical presence of God.
Sikhs believe that the Sri Guru Granth Sahib is so magnificent in its design, that it is actually like a computer through which you may directly ask God your questions and get your answers.
This is the role the Gurus fulfilled during their time on earth, and yet the Guru’s blessings are even greater than that.
Sikhs view the Siri Guru Granth Sahib as their Living Guru, and feel the Shabd Guru holds our hand and takes us into the awareness of divine consciousness and the presence of God.
~Resource: Living Reality (1994) by Bibiji Inderjit Kaur Khalsa.