The belief in the Family Guy character, Stewie's, beliefs in world domination. This belief comes with the urge to quote the character.
Stewieist: Damn you all!
Guy: Dude, you believe is stewieism?
A man who believes in the all-father Stewie. They are commonly reffered to as faggot or my bitch.
Guy: heil stewie
other guy: oh no he practices Stewieism