Seth Godin has a brief post on belief. Database Marketers, especially those who work in the field of Business Intelligence, struggle with belief. Anytime a BI person has to share facts with people, beliefs are likely to override facts. If I had a dollar for every person who believed their opinions over my facts, I wouldn't have to work anymore.
The best you can do is work with honesty, integrity and humility. If people choose to disagree with your facts, let 'em. Show that you consistently act with honesty and integrity, and over time, people will be more likely to agree with your information. Database Marketing and Business Intelligence are about the long-haul, not about making a short-term splash.