If we take shelter of the lotus feet of the spiritual master, we can become free from illusion, fear, and distress. If we wholeheartedly beg for his mercy without any deceit, then the spiritual master bestows all auspiciousness upon us.
A pure devotee knows that everyone is the spiritual master. Therefore, a pure devotee can be jagad-guru.
There is no work as auspicious as serving the spiritual master. Of all worship, the worship of the Supreme Personality of Godhead is the greatest. But the worship of the lotus feet of the spiritual master is even greater than the worship of the Supreme Personality of Godhead. Unless this is firmly realized we can not understand what saintly association means; we cannot understand what the shelter of a spiritual master means; we cannot understand that we are dependent and he is our maintainer.
In order to teach us how to serve Him, the Supreme Personality of Godhead Himself appears as the spiritual master.
A bonafide spiritual master is non-different from Supreme Personality of Godhead. If one cannot say that the spiritual master is the personal manifestation of the Supreme Personality of Godhead, one will not be able to utter the holy name of the Lord.