Most people have faith that they are right, but they don't have knowledge that they are right. Looking at three categories of people is helpful to understand this distinction, self-affirmers, extreme fighters, and shallow divers.
Self-affirmers are those people who mainly interact with people of their own persuasion. They don't read books or listen to people who think differently then them, especially if the topic is contrary to what they believe. In this case ignorance is bliss and they intend to stay that way. It is the type of person who tries to give you a book about what they believe, but will not read a book about what you believe. They are sure in their belief because nobody is given a chance to contradict it.
Extreme fighters are those people who take the most extreme position as defining an opposing viewpoint. Straw men and sweeping generalizations are characteristics of extreme fighters, and they don't find it odd that only their perspective cannot easily be dismissed. These people rarely understand their own views but are vocal in the denunciation of other views. It is the type of person that goes quiet or into a rage when confronted. Their views are maintained emotionally not rationally.
Shallow divers are people who interact with others only to prove their point, but do not seek to understand another's perspective. They look to find what they are looking for, but don't look too closely in case they find something they don't want to see. Astute at seeing the contradictions in differing perspectives, but they don't apply the same rigour to their own perspective. Outwardly winsome to those who agree, outwardly ignorant to those who disagree.
The errors of these types of people springs from the failure to recognize that everybody thinks they are right (even themselves), which I have written about in more detail here. Thinking that you right is not evidence that you are right, because that is exactly what you should expect. As a result, they don't account for the effect of their assumptions. Assumptions are things that creep into the definition of words, not the use of them. For example, love is more associated with emotional ecstasy, than steadfast commitment for some. "I love this shirt," makes sense to one person, but is complete none sense to someone else depending on how they define love. The insidiousness of assumptions is that we do not always know when we are applying them. This is why we need to dive deep into other people's perspective, to fully know our own.
We all exhibit the characteristics of being self-affirmers, extreme fighters, and shallow divers, because of fear. It takes courage to try and truly understand a different perspective because it may mean some big changes for us. The truth does not change because of conflict, rather it is sharpened and cuts through the assumptions of those in conflict. Truth is not assumed, it is found.