Doubt, uncertainty, or scepticism regarding the existence of a god or gods.
1956, January 31ˢᵗ: Alan Alexander Milne; quoted in:
1988: James B. Simpson, Simpson’s Contemporary Quotations, № 4,393 (Houghton Mifflin, →ISBN
The Old Testament is responsible for more atheism, agnosticism, disbelief — call it what you will — than any book ever written; it has emptied more churches than all the counterattractions of cinema, motor bicycle and golf course.
(by extension) Doubt, uncertainty, or scepticism regarding any subject of dispute.