Acharya Prashant explains that the greatest mistake of humanity is establishing the ultimate truth or God outside of oneself. He argues that if the most valuable, peaceful, and true entity is considered external, then the individual inherently becomes small, false, and empty. This perceived void leads to a lifelong struggle to find God, which is often reinforced by scriptures and teachers who suggest that divinity is something to be attained. He asserts that terms like God, Truth, Compassion, and Liberation are all names for one's own essential nature. By seeking these externally, one falsely accuses oneself of having lost them, creating a cycle of search that can never end because the seeker has already assumed their own untruth.