The rituals and rigid beliefs of people with obsessive compulsive disorders are very powerful. In popular culture we tend to look at things like compulsive handwashing, or the need to eat certain things at certain times of an eating disorder as just extreme thinking.
And we try to reach the person with reason and facts.
I think it is better if we understand that it is us who don't get it, not them. We don't get how very strong these cognitions are, how primal the fear, and how a particular part of an otherwise rational life can be so far removed from the reality we live in.