The Meaning of "God"
Knowing what one is talking about is of inestimable value in any dialogue, so the theist, before he sets out to explain why we should believe in god, must first explain what he means by the word "god". What is the theist attempting to establish the existence of? What is the nature of god? How are we to identify him (or it)? At least some of the attributes of this supposed creature must be known before anything can be considered relevant to establishing his existence. As one theist puts it, "With no description or definition to work from, we will literally fail to know what we are talking about." For example, consider the following dialogue:
Mr Jones: "A unie exists."
Mr White: "Prove it."
Mr Jones: "It has rained for three consecutive days—that is my proof."
If this exchange is less than satisfactory, much of the blame rests with Mr. White: his demand for proof is immature. Mr. Jones has not specified what an "unie" is; until and unless he does so, "unie" is nothing but a meaningless sound, and Mr. Jones is uttering nonsense. Without some description of an "unie," the alleged proof for its existence is incoherent.
When confronted with a claim that a god exists, the person who immediately demands proof commits the same error as does Mr. White. His first response should be, "What is it for which you are claiming existence?" The theist must present an intelligible description of god. Until he does so, "god" makes no more sense than "unie"; both are cognitively empty, and any attempt at proof is logically absurd. Nothing can qualify as evidence for the existence of a god unless we have some idea of what we are searching for. Even if it is demanded that the existence of god be accepted on faith, we still must know what it is that we are required to have faith in. As W.T. Blackstone puts it,
Until the content of a belief is made clear, the appeal to accept the belief is beside the point, for one would not know what one has accepted. The request for the meaning of a religious belief is logically prior to the question of accepting that belief on faith or to the question of whether that belief constitutes knowledge.
from Atheism: The Case Against God
by George H. Smith