It is difficult to fathom the thinking of some people - though they may be sincere in their beliefs. This is because of a number of factors:
a. Some people are deep. They have minds that probe a long way down into the cause and effect of life. As you follow their thoughts, the light from the surface grows dimmer, and at last fails to illuminate anything. If you are still trying to read or listen, nothing is seen or heard.
You have passed your capability to perceive...and sometimes the other person has taken you there deliberately.
b. Some people are shallow. They have the intellectual depth of a mud puddle, and their thoughts have the same clarity and consistency, too. You cannot understand what they say because their waters of wisdom are mostly stirred dirt.
c. Some people are dry land thinkers. You can only get into their thoughts by sifting dust. It may be the dust of centuries of dogma or the faerie dust of current meme-times, but it is an unpleasant thing to encounter. Try not to sneeze.
On the opposite side of the mental street are the thinkers who show their minds to you with absolute clarity...even when you don't want to look. The honest ones shine their light and let those who will, see by it - the enthusiasts insist upon dazzling all they can catch. If you shade your eyes or close them to preserve your own thoughts you become guilty of ignorance or stupidity and can expect to be scolded.