Chris Mooney has a post in which he charts the influence of politics and religion on science denial.
At the end, he concludes that our sense of personal identity is the major influence.
I've found that money and a misguided sense of fairness are what really contributes to science denial.
Money (profits) motivate certain people to manufacture science denial propaganda, which convinces others into denial.
A sense of fairness (misguided) gives the people who manufacture the science denial propaganda an outlet to distribute the propaganda they've manufactured. For example, in journalism, journalists feel they must portray two sides of a story in order to be fair. A journalist covering global warming may feel compelled to allow a global warming denier to have his/her say. A person reading or watching the journalist's product will then be confused on the scientific consensus and may be drawn into science denial.
If more people understood the importance of the methodology of science (input = peer reviewed studies, output = scientific consensus bodies' conclusions), they wouldn't be drawn into denial, regardless of politics or religion.