If a insurance company puts "act of god" in its policy should they not have to prove the existance of god in the event of trying to avoid paying out, I know some now put "act of nature" instead of this.
There's a Billy Connoly film 'The Man who Sued God', his fishing boat is destroyed, therefore destroying his livelihood, the insurance company tells him it's an act of God so he sues God (through his representatives on Earth) the church for destroying his boat. Alright film!
Other than Nichols v Marsland in 1876 there has been no other case in English law where Act of God has been succesful as a defence, and is now considered obsolete.