Found the following quote on Richard Dawkins Site and thought I'd counter a few of these points too while I'm at it.
Six Reasons to be an Atheist from The Little Book of Atheist Spirituality by Andre Comte-Sponville
1. The weakness of the opposing arguments, the so-called proofs of God's existence
2. Common experience: If God existed, he should be easier to see or sense.
3. My refusal to explain something I cannot understand by something I understand even less.
4. The enormity of evil.
5. The mediocrity of mankind.
6. Last but not least, the fact that God corresponds so perfectly to our wishes that there is every reason to think he was invented to fulfill them, at least in fantasy; this makes religion an illusion in the Freudian sense of the term.
These are not Dawkins own reasons but they are on his site so here we go:
1. Weakness of an opposing argument should not be cited as a reason to reject God. The theory that the Earth was flat was accepted because this was the argument that made most sense, the weakness of the opposing argument meant that it was rejected. It was only when it was proven to be correct was it accepted. Mankind has been wrong about many things in the past in regards to science and while neither the existence and non-existence of God may ever be proven correct, it would be arrogant and ignorant to rule out the possibility based on the weakness of the counter argument.
2. Science again provides an example where this is plain arrogance. Dark Matter could neither been seen nor sensed only a few years ago and yet today as our instruments of detection have improved we can now sense it. The idea that man has reached some sort of level whereby he somehow can see or sense everything is once again arrogant and ignorant.
3. Surely this is something science does everyday. Psychologists explain human thought and processes in the brain using structures that they themselves admit they do not fully understand. I do admit though that everything in the Universe should be able to be explained simply because I think God created it to follow rules that we are intelligent enough to one day grasp. Does not mean there is no God though.
4. Give me a break! If I could prove that the enormity of good in the world balances the amount of evil would we then say that there is a God?
5. Mankind is mediocre because he has not finished evolving yet but if you follow what some religions state then the mediocrity of mankind is perfected when death moves you beyond the physical form. Why do we think that we are the pinnacle of evolution at this point in our existence. We have so much more to learn and are such a young species that perfection may be a point that can met through further evolution. Perhaps that is what is meant by heaven on Earth. When the species evolves to the point where we are perfect then God will be known to us. Just a thought but at least I'm not giving the impression that mankind is somehow as good as evolution gets.
6. Probably the best argument of the 6 to be honest and also the easiest to refute. If you believe in Christ then it's been 2000 years since God contact mankind directly. In this time we have analysed time and again the words we were left and with our flawed minds we set our own understandings loose on the World. We altered the image to suit ourselves and applied man-made rules to teachings without being told that the rules were right or wrong. This is not proof that God exists or not and is certainly not reason to give up religion it is simply the fact that man alters things to fit with his own understanding. In the same way as we have altered people in history to do many super-human feats they probably never did we altered God to fit with our hopes and dreams. The fundamental rules may be correct just our image may be distorted by time. Doesn't mean he doesn't exist though.