Sure, negativity can work. Negating the people who don't think the way you do is always a way to create change in the world. But that's sort of, well, not good. Negative being the opposite of positive. Which is, as the title says up there, the opposite what they are trying to say here. It's giving a mixed message, at least on the subconscious level (and on the conscious level for us language geeks). When you define yourself as being against something, you not only make yourself out to seem negative (not good), you also strengthen the beliefs of those who appreciate that something you are attacking. Sometimes you get lucky and things work out, but it's a bad (negative) strategy that sucks up huge amounts of resources.

The better way to go is to simply promote the specific thing that they DO believe in (curiosity about how the universe works, testing theories, revising knowledge based on new information, whatever it is that they most believe in...) as being good.