When a pure devotee or spiritual master speak, what he says should be accepted as having been directly spoken by the Supreme Personality of Godhead in the Parampara System. — Sri Caitanya Caritamrita, Antya Lila, 05.71.
The genuine Guru is God’s representative and he speaks about God and nothing else.
Holy name alone is sufficient to take you back home back to godhead. However to cultivate the mood of surrender You need a Guru.
Out of many millions of wandering living entities, one who is very fortunate gets an opportunity to associate with a bonafide spiritual master by the grace of Krishna. By the mercy of both Krishna and the spiritual masters, such a person receives the seed of the creeper of devotional service.
In the Bhagavat culture worship of the spiritual master plays a very important role in our life.