Richard Dawkins claims in The God Delusion (p. 137) that “there almost certainly is no God”. This is false and misleading. We can deny the existence of the God of Judaism, Islam and Christianity with one hundred percent confidence.
“How can you say that? You don’t know everything!”
What a strange thing to say. I have never claimed to know everything. I’m not sure the idea even makes any sense.
“The point is, you could be wrong about how the world works.”
I’m sure I am. Sooner or later something I observe will force me to adjust one or more of my ideas about how the world works. It could happen today. It could happen many times today. But what I observe will certainly not be the God of Abraham.
I know this first of all because the Christian God is unobservable. At least, that’s what everyone answers, when we ask why it’s never observed.
But there is a more important reason that God can’t pop up and let all of us know that we were wrong: the definition of God is incoherent. This means that God cannot exist, by definition.
Richard Swinburne, a highly respected theologian, writes (The Coherence of Theism, 1993, page 1) that a theist is
a man who believes that there is a God. By a ‘God’ he understands something like a ‘person without a body (i.e., a spirit) who is eternal, free, able to do anything, knows everything, is perfectly good, is the proper object of human worship and obedience, the creator and sustainer of the universe’. Christians, Jews and Muslims are all in the above sense theists.
Swinburne follows millennia of mainstream monotheism in saying that God is omnipotent and perfectly good. But the Euthyphro argument and the problem of evil show that this does not make sense. Omnipotence and omnibenevolence are mutually exclusive. (In fact, each one is probably incoherent all by itself.) Therefore, his definition is logically incoherent. It follows with logical certainty that his God, the God of mainstream Judaism, Islam and Christianity, cannot exist. There is no almost.
By the way, ‘logically incoherent’ does not mean ‘disputable on semantic terms if you have a degree in philosophy’. It means, ‘doesn’t make sense’.
Imagine that someone tells you of an object that is “perfectly round and perfectly square.” If you accept the claim that the object is ‘perfectly round’, it becomes impossible to understand the claim that it’s ‘perfectly square’; and vice versa. An object can’t be both those things. Why? Because of what the words ’round’ and ‘square’ mean! It’s that simple, and that certain.
Dawkins’s “almost” is much too weak. We know for a fact that the traditional God of monotheism cannot possibly exist. We have merely to look unflinchingly at the concepts included in its definition. ‘Perfectly good’ and ‘perfectly capable’ contradict each other, as surely (though not as obviously) as ’round’ and ‘square’. Therefore, the definition of God fails to make sense. The atheist has no need to disprove it, because the existence of God has never even been coherently proposed.
YASHWATA 
Consider everything? I’m afraid I don’t have that kind of time.
But consider Swinburne’s definition of God as “a person without a body.” The phrase doesn’t make sense, because all the persons we have ever known have had bodies. What would a person be without a body? What do we know about the attributes of such an entity? All we know is that it doesn’t happen. A person without a body is not a person.
“Well, fine,” you might say. “This ‘person without a body’ is not a person, it’s God!”
But then what is the word “person” doing in there? It’s only telling us what God is not. So we should leave that part out, and say that God is a mysterious something-or-other without a body. And now the “without a body” part sounds weird. Again, it’s only telling us what God is not. What are the positive attributes? We don’t know. No one knows. Nothing is known about God. Not a single thing.
The word “God” is a placeholder. It refers to nothing at all. It’s a meaningless sound. Why does it exist? Here’s one theory: the purpose of that word is to make it hard for people to have rational conversations about practical things. It is a weapon.
A way to get around euthyphro… It is good because it is in god’s nature… and Evil exists because True Free will cannot exist without evil… and if those two arguments disprove a God, then why do people argue the subject today? How do you get around Robert madel’s Modal Prefection Argument, Alvin Plantinga’s Modal Ontological Arugument, Kalaam Cosmological argument? Consider everything before making such bold statements.
I agree, Janet. The old gods were more plausible. If you asked someone, “What makes you think there’s a thunder-god,” he could say, “Listen to that, dude! Does that not sound like a god to you?” Maybe not perfectly convincing on a philosophical level, but at least there’s something there. In modern theology, god is perfectly imperceptible. That’s an awfully weak position to take regarding one’s favorite thing in the universe.
I think the reason that Dawkins says ‘almost certainly’ is that every individual has a different explanation of what they mean by ‘god’ and probably a new one every day which makes it very difficult to say ‘there is no god’. It depends what you mean by ‘god’. The Abrahamic god clearly doesn’t exist, and I can’t think of a god that might exist which is of any use or importance in the universe. Actually I can’t think of a god that might exist. None of them make any sense.
What about the old Greek gods which have always seemed to me to be much more consistent with the world as we see it around us? They were not all good or all knowing or all anything, and they certainly didn’t promise that you’d get everything you asked for either. Believing in a world ruled from Olympia would make some sense at least, might explain some of the chaos!