In Chaos Magic, beliefs are not seen as ends in themselves, but as tools for creating desired effects. To fully realize this is to face a terrible freedom in which Nothing is True and Everything is Permitted, which is to say that everything is possible, there are no certainties, and the consequences can be ghastly. Laughter seems to be the only defence against the realisation that one does not even have a real self.
The purpose of Chaos Rituals is to create beliefs by acting as though such beliefs were true. In Chaos Rituals you Fake it till you Make it, to obtain the power that a belief can provide. Afterwards, if you have any sense, you will laugh it off, and seek the requisite beliefs for whatever you want to do next, as Chaos moves you.