Ignosticism
Ignosticism is the lack of belief that God means anything at all -- nothing that exists nor anything that does not exist.
Ignostics claim that the sound and letters "God" (with a capital "G") and "Allah" are meaningless because there has never been a coherent definition of the word.
Ignostics argue that monotheists use circular reasoning when they say that "God made everything that exists except God". This defines "God" in terms of "God", and also gives no description for "God" since "what something did" is not the same as "what something is".
It is considered synonymous with theological noncognitivism.