The sure — and only — downfall begins the moment one forgets/does not revere/criticizes/betrays one’s own guru.
According to Sri Guru Gita, a spiritual masterpiece that reveals profound secrets of the Guru Disciple relationship, “Continue to remember the Guru to the end of time. Never forsake the Guru, even after attaining spiritual liberation.”
यावत्कल्पान्तको देहस्तावदेव गुरुं स्मरेत्.
गुरुलोपो न कर्तव्यः स्वच्छन्दो यदि वा भवेत्.102.
Yāvatkalpāntako dehastāvadeva gurum smaret |
Gurulopo na kartavyaḥ svacchando yadi vā bhavet || 102 ||
Usually, a seeker, who has been doing spiritual practices, begins to develop Siddhis (spiritual powers) and then forgets that the true source of these powers is the Guru. Once this happens, the seeker may become attached to these spiritual powers and then begin to proclaim himself/herself a “guru” to look for followers.
Nijaguna Shiva Yogi (a spiritual master in the 15th century) said, “Once you receive Guru’s grace [Shaktipat or kundalini awakening], it will never leave you, no matter how many lifetimes you go through. The Guru’s grace will continue to chase you.” Truly speaking, a true guru’s child can have no downfall. However, one must really belong to the guru.
To learn more, please refer to the book, Building a Noble World (ISBN: 978-0974919706).