...Guru, which means "one who destroys/dispels darkness". 'Gu' is darkness and 'ru' is destroyer.
Ultimately, it is said that Guru, Self and God are one and the same.
Guru is the Self. When existence becomes unbearable for the ego, Self manifests as God, as Guru, as Saguna -- to push the ego in. Guru is friend, lover, Lord, a close confidante. One can carry Guru on one's shoulder and carry on a private talk. The normal people will mark such behaviour as of a mad man but it is that only. Guru only can teach that this world is mad and fake.