Open Question: Is a volcano an act of God? How can insurance companies prove God is to blame for natural disasters?

The volcanic ash spewed out from the eruption on Iceland has resulted in thousands of flights in the U.K. and northern Europe being cancelled. Some people will not be able to claim for financial loss because insurance companies are using the "act of God" get-out clause. Is there a legal precedent where an atheist/scientist/geologist has successfully challenged an insurance company on the basis that volcano's, earthquakes etc., are acts of nature rather than acts of God? Should the insurance companies not be made to prove (a) that God exists, (b) which God they mean and (c) provide evidence that God was to blame. Perhaps insurance companies should be made to change the wording to "an act of nature" to be (a) politically correct and stop offending atheists and (b) theologically correct and stop offending Christians, Muslims, Jews, etc., etc.