Reading the entire article will give you some sense about why it is so difficult to change irrational belief systems in some people. Keep these points in mind when challenging those who may embrace radical ideologies.
Skeptical thinkers must realize that because of the survival value of beliefs, disconfirming evidence will rarely, if ever, be sufficient to change beliefs, even in "otherwise intelligent" people. In order to effectively change beliefs skeptics must attend to their survival value, not just their data-accuracy value. This involves several elements.
First, skeptics must not expect beliefs to change simply as the result of data or assuming that people are stupid because their beliefs don't change. They must avoid becoming critical or demeaning in response to the resilience of beliefs. People are not necessarily idiots just because their beliefs don't yield to new information. Data is always necessary, but it is rarely sufficient.
Second, skeptics must learn to always discuss not just the specific topic addressed by the data, but also the implications that changing the related beliefs will have for the fundamental worldview and belief system of the affected individuals. Unfortunately, addressing belief systems is a much more complicated and daunting task than simply presenting contradictory evidence. Skeptics must discuss the meaning of their data in the face of the brain's need to maintain its belief system in order to maintain a sense of wholeness, consistency, and control in life. Skeptics must become adept at discussing issues of fundamental philosophies and the existential anxiety that is stirred up any time beliefs are challenged. The task is every bit as much philosophical and psychological as it is scientific and data-based.
Third, and perhaps most important, skeptics must always appreciate how hard it is for people to have their beliefs challenged. It is, quite literally, a threat to their brain's sense of survival. It is entirely normal for people to be defensive in such situations. The brain feels it is fighting for its life. It is unfortunate that this can produce behavior that is provocative, hostile, and even vicious, but it is understandable as well.
The lesson for skeptics is to understand that people are generally not intending to be mean, contrary, harsh, or stupid when they are challenged. It's a fight for survival. The only effective way to deal with this type of defensiveness is to de-escalate the fighting rather than inflame it. Becoming sarcastic or demeaning simply gives the other person's defenses a foothold to engage in a tit-for-tat exchange that justifies their feelings of being threatened ("Of course we fight the skeptics-look what uncaring, hostile jerks they are!") rather than a continued focus on the truth.
Skeptics will only win the war for rational beliefs by continuing, even in the face of defensive responses from others, to use behavior that is unfailingly dignified and tactful and that communicates respect and wisdom. For the data to speak loudly, skeptics must always refrain from screaming.
Finally, it should be comforting to all skeptics to remember that the truly amazing part of all of this is not that so few beliefs change or that people can be so irrational, but that anyone's beliefs ever change at all. Skeptics' ability to alter their own beliefs in response to data is a true gift; a unique, powerful, and precious ability. It is genuinely a "higher brain function" in that it goes against some of the most natural and fundamental biological urges. Skeptics must appreciate the power and, truly, the dangerousness that this ability bestows upon them. They have in their possession a skill that can be frightening, life-changing, and capable of inducing pain. In turning this ability on others it should be used carefully and wisely. Challenging beliefs must always be done with care and compassion.
Skeptics must remember to always keep their eye on the goal. They must see the long view. They must attempt to win the war for rational beliefs, not to engage in a fight to the death over any one particular battle with any one particular individual or any one particular belief. Not only must skeptics' methods and data be clean, direct, and unbiased, their demeanor and behavior must be as well.
Read the rest. It is worth it. Knowledge is Power.