"To show that an argument is invalid or unsound is not to show that the conclusion of the argument is false...All the proofs of God's existence may fail, but it still may be the case that God exists. In short, to show that the proofs do not work is not enough by itself. It may still be the case that God exists."
(Kai Nielsen, Reason and Practice (New York: Harper & Row, 1971), pp. 143-4. cited at: http://www.origins.org/articles/craig_tooley_3.html)