Before his Islam film, he was known for being an activist for abolishing the Dutch monarchy, for supporting militant homosexuals, for idealizing deviant sexuality, for making fun of Catholics and Reformed Christians, and for mocking the Holocaust and Anne Frank.
When Evelien Gans, who is a fairly prestigious historian of the Holocaust, wrote a letter to a newspaper criticizing van Gogh for telling Holocaust jokes on TV, van Gogh responded by telling her that he knew "she just gets wet dreams about being f***ed by Dr. Mengele." He usually expressed himself with that level of vulgarity - very reminscent of Bill Maher in both the crudeness of his talk and the anticonservative rhetoric he continually espoused.
Van Gogh was a total scumbag - the point is that conservative Dutchmen, the Dutch royal family, Christians and Jews all criticized him verbally. The only people he mocked who responded with violence were Muslims.
His life proves that the Christians and conservatives he portrayed as "intolerant" were not at all.