1
general::
An unforeseen and uncontrollable natural event, such as a hurricane, fire, or flood. For example, The publisher shall publish the work within twelve months except in case of delay caused by acts of God such as fires or floods or other circumstances beyond its control. It most often appears in legal contracts, where it is used to indemnify one party against a disaster that prevents it from carrying out the contract's terms. [Mid-1800s]
American Heritage Idioms
2
general::
Phrase(s): an act of God
an occurrence or an event for which no human is responsible; an act of nature such as a storm, an earthquake, or a wildfire. • Will your insurance company pay for damage caused by earthquakes and other acts of God?
McGrawhill's American Idioms And Phrasal Verbs