Milk is very good and nourishing, but when it is touched by the mouth of a snake it is no longer nourinshing; rather, it becomes a source of death. Similarly those who are not strictly in the Vaisnava discipline should not make a business of Srimad Bhagavatam and become a cause of spiritual death for so many heares.
One should understand Krishna in truth and this one can do only by serving a pure devotee. — Srimad Bhagavatam, 07.09.24.
The Krishna consciousness movement is therefore distributing sublime information to the entire human society to the effect that by simply chanting the Hare Krishna mantra one can become perfect in this life and go back home, back to Godhead.
Bhagavad Gita 9.25,
Srila Prabhupada
One may or may not know the power of chanting the Hare Krishna mantra, but if one chants the holy name he will become free from all sinful reactions.
Srimad Bhagavatam 6.2.18,
Srila Prabhupada
One should try to purchase a ticket to go back home, back to Godhead. The price of such a ticket is one’s intense desire for it, which is not easily awakened, even if one continually performs pious activities for thousands of lives. All mundane relationships are sure to be broken in the course of time but once one establishes a relationship with the Supreme Personality of Godhead in a particular rasa, it is never to be broken, even after the annihilation of the material world. — Sri Caitanya Caritamrita, Adi Lila, Chapter 01, Text 56.
Ecstacy is only available by spiriutal indulgence. Material nature can’t give us everlasting happiness, which our heart is searching for.
By surrendering and praying for the causeless mercy of the Lord, the devotee can progress on the path of complete self-realization
Srila Prabhupada’s purport on Sri Isopnishad Mantra 18
That procedure which in the beginning may be just like poison but at the end is just like nectar and which awakens one to self-realization is said to be happiness in the mode of goodness.