No, because if they believe what they believe, then to them it is so. That's what the Poyozo doll and Spekkio tried saying I'm guessing.
If you believe in Fate, then you're bound to it because you know that whatever you do, you're insignificant. If you don't believe in it, then you have an excuse to think back and say "Damn, I should have done something better" etc.
Like with Spekkio saying "If i'm weak, you're weak. If I'm strong, you're strong", it basically reflects the person.
Wasn't it also how Chronopolis explained the universe? That it's only perceived by those who view it from themselves or something. Basically, FATE would ultimately exist, but to the non believers, they have a motive to say that it doesn't exist so they can have a clear conscience to know that they have free will, even tho someone above would know everything.
Otherwise, we'd have a choice to not save the planet, lol.