Religion

it's not the only one. A lot of anti-vaxxers are not basing their opposition on religion, but on unscientific woo-based opinions of the likes of the discredited British doctor, Andrew Wakefield, who claimed without scientific support that vaccines cause autism. Robert Kennedy is another high-profile anti-vaxxer. Of course, anti-vax "science" is a sort of religion in the sense that once people believe it, their belief is impervious to any actual science. Woo-believing anti-vaxxers tend to be on the left of the political spectrum, while religious anti-vaxxers tend to be on the right, but both are equally stupid.