I mean you really can’t question it. Any argument will be reduced to:
“just a thought” or “everything is imagination” or “you are a materialist”
or “you are thinking too much and over analyzing” or “who’s asking?”.
Of course we are separating here the actual practice of non-duality
from the ideas about it.
Please, don’t get me wrong here, I’m a seeker myself, and a very diligent one.
I’ve been on this path for more than 6 years, and my skepticism
comes from a loving place. Speaking of Open-Mindedness this
value got me very very far, and I believe that a healthy skepticism
plays an important role in keeping an open mind. Why?
Because in order to open your mind to new possibilities you
must have the ability to question your current paradigm.
Self Actualization Journal 