'the impossibility of God' a book, which proves that God cannot exist, basically. It takes every attribute of God and attempts to prove each are impossible, incoherent, or inconsistent in combination with the other attributes.
God attributes include: omnipotence, omnipresence, omniscience, omnibenevolence, He is perfect, immutable, transcendent, nonphysical, personal, free, all-loving, all just, all-merciful and the creator of the universe.
The book also looks at religious doctrine and shows it to be inconsistent etc.
It may be impossible to prove that a being doesn't exist which may be considered creator/ruler of the universe. But it is relatively simple to prove that "God" does not and cannot exist.