That is a good question. And, yes, fakes abound all around duping innocent folks. But, how do you know that there is really something called "inner light" and "inner sound"? Also, what do you mean by these terms? Do you mean "light that emanates from the soul but is hindered by the senses" as in some eastern mystic religions? Or, do you mean "light of the Creator God, of the Logos, that enlightens a believer but is resisted by a sinner" as in Christianity?

I am not certain if it would meet your expectations, but I know of one person who can go into an open field, walk in a circle, and invite someone to join inside the circled area, and the person invited in, although unable to see any defining boundaries would be able to hold one finger vertically and trace the boundaries with one side of the finger in the circle and the other side outside, and note that the inside felt much better than the outside.

Ki, I have a solution for you. Abandon your belief in supernatural gods and consciousnes-based spirituality and live in the moment. All your difficult questions cease to be askable. Problem solved!

De nada!