The root cause of material existence is the lack of faith in the Supreme Personality of Guruhead. Although externally professing to be staunch followers of the disciplic succession, unfortunate persons have no faith in the words of the Supreme Personality of Guruhead and thus they create innumerable obstacles on the path of bhakti for them and their followers. Instead they worship minor, less important men and equalize the Supreme Personality of Guruhead with them.
No bona fide guru claims to be a successor of the Supreme Guruhead on the basis of his physical absence. In fact, there is no such physical nor spiritual absence. The Supreme Guruhead, just like the Supreme Godhead is identical with his vibrational representation and any bona fide preacher is the emblem of that understanding. But mundane people in the dress of devotees, who are overly attached to the material covering of the spirit soul that consists of skin, flesh, stool and bones unnecessarily mix the spiritual understanding with material concepts of life and thus create confusion for the general public and send them to the lower regions of hell.
One must therefore make the Supreme Personality of Guruhead, his only and exclusive shelter and, initiated by his holy sound, spread the bona fide non-dual worship of the Supreme Lord Krishna far and wide.