The Overton window is an expression that refers to the range of ideas common and acceptable in the mainstream.
When your beliefs fall within the Overton window, it is easy to feel a sense of confidence in what you believe due to the presence of like-minded individuals and the ease of finding documentation to support your beliefs.
Confidence might be justified for some of these beliefs, but not for others. The mainstream is not always right.
Although it is certainly possible to feel a sense of confidence despite being a non-conformist if you know your sources, the more your beliefs fall outside the Overton window, the more difficult it becomes to communicate (and the more likely you are to be dismissed as a crank). Communication relies on a vast compendium of mutual and mutually understood experiences, expectations, idioms, metaphors, mental and verbal short-cuts, and reactions. Straying outside the Overton window jeopardizes all this.
The less you have in common with someone, the harder it is to communicate. Just try reading Japanese literature or manga. The first time I encountered manga I found it incomprehensible.
I also found Ann Coulter incomprehensible at first due to the rapidity with which she was navigating around ideas which were socially unacceptable, such as the constant disrespect she was showing for individuals whom the mainstream media showers with endless accolades. I could not tell when she was joking and when she was being serious. It took me a while to get familiar with the non-conformist ideas with which she was operating.
In regards to personal interactions, the key to overcoming this sort of communication barrier is of course patience, on both sides. This also required time. If there is no patience or time, communication becomes impossible.