Is everything in zeitgeist the movie false?

Xians often say that nothing in zeitgeist the movie is true, however towards the beginning of the film is the sum 1+1=2 written on the screen Now are xians saying that 1+1 does not equal 2? I'm confused. But if they accept that is correct then how do we know that other parts of the film arent true either, such as the son god = sun god bit? Xians just dismiss everything that doesnt fit their narrow bigoted views even when it means claiming 1+1 does not equal 2. How can you debate with people who dont accept basic maths?