“As stated in the Vedic literature (Bhag. 11.20.17):
nr-deham adyam sulabham sudurlabham plavam sukalpam guru-karna-dharam
We, the conditioned souls, have fallen in the ocean of nescience, but the human body fortunately provides us a good opportunity to cross the ocean because the human body is like a very good boat. When directed by a spiritual master acting as the captain, the boat can very easily cross the ocean. Furthermore, the boat is helped across by favorable winds, which are the instructions of Vedic knowledge. If one does not take advantage of all these facilities to cross the ocean of nescience, he is certainly committing suicide.
One who boards a boat made of stone is doomed. To be elevated to the stage of perfection, humanity must first give up false leaders who present boats of stone. All of human society is in such a dangerous position that to be rescued it must abide by the standard instructions of the Vedas. The cream of these instructions appears in the form of Bhagavad-gita. One should not take shelter of any other instructions, for Bhagavad-gita gives direct instructions on how to fulfill the aim of human life. Lord Sri Krishna therefore says, sarva-dharman parityajya mam ekam saranam vraja: “”Give up all other processes of religion and simply surrender to Me.”” Even if one does not accept Lord Krishna as the Supreme Personality of Godhead, His instructions are so exalted and beneficial for humanity that if one follows His instructions one will be saved. Otherwise one will be cheated by unauthorized meditation and gymnastic methods of yoga. Thus one will board a boat of stone which will sink and drown all its passengers.”
Source: A.C. Bhaktivedanta Swami Prabhupada (2014 edition), “Srimad Bhagavatam”, Sixth Canto, Chapter 07 – Text 14