Just when you thought you heard it all...

[zahratustra]

It's too simple - just so simple that you won't believe in my answer :

No-one is telling them the truth.

....

It's as simple as that.
It explains one way (of many) of how people come to "believe" in things.

It doesn't explain why only some people do believe in crazy shit Alrik.

 

[Alrik Fassbauer]

Because no-one has told them how/what shit looks like. Especially crazy shit.

 

[Jack]

Grandfather Nurgle smiles upon America.