An atheist will encounter many and varied claims for the existence of a particular deity. It only seems reasonable to ask for some sort of tangible evidence to back up these claims, does it not? After all, if I ran into the room and shouted "I have just seen a UFO! I was this close to being abducted!", you might not immediately take my word for it. You might well ask for some evidence, such as a photograph (autographed if possible), or strange alien artifact. You might go to the location where I claim to have seen the spaceship, and inspect it for yourself. You could probably think up a number of alternative explanations for what I said I saw. If I fail to support my claims, why on earth should you take my word for it?
Many of the more common claims that are made to demonstrate the existence of a god seem to be fatally flawed. If you've chatted with theists on the internet, your doorstep, or whereever, you may be familiar with these :
"Look around you! How can you witness the beauty of God-X's Creation and still disbelieve. Look at the trees, the birds, the bunnies!"
What's wrong with this? Several things:
* Many other religions make exactly the same claim. Why is your one special? Surely the trees, bunnies etc. are therefore equally valid proof of the existence of hundreds of other gods? One supernatural explanation is just as valid as any other.
* Unfortunately, everything you describe can also be explained in mundane, rational, scientific terms, without the need to invoke a Creator.
* What about the nasty things in life? Guinea worms, anthrax, mosquitoes; all the blood-sucking, parasitical, disease-bearing, poisonous beasties that kill us and each other in horrific ways? Watched any nature programmes recently?
"Six hundred million people follow my religion. They can't all be wrong - there must be something in it."
What's wrong with this? Several things:
* Nine hundred million people follow religion Z. Are they all wrong? Truth is not democratic - you can't vote for objective reality.
* Maybe they are right. Maybe their god exists as well as your god?
* If they're wrong, couldn't you also be wrong? After all, they seem to believe at least as strongly and sincerely as you do, and for many of the same reasons...
"I have personally witnessed a miracle. I can trust my senses."
What's wrong with this? Several things:
* Lots of people have personally witnessed Elvis working at the Drive-Thru. Should I believe them also? Without any sort of evidence, personal subjective testimony is not very convincing.
* Many people from other religions claim to have witnessed miracles. Does this mean that their God also exists? Just how many Gods are there?
* Are you positive that Divine Intervention is the only possible explanation for what you saw?
"My God is a living God. All those other ones are just ancient myths."
What's wrong with this? Several things:
* Those gods were "living Gods" to the people who believed in them. Zeuss, Odin and Jupiter once had followers every bit as devout as you.
* Many of the "ancient" religions still have active, devout, sincere followers. Just like you. Why should I accept your claims over theirs identical ones?
* How many people claim to worship dead gods?
"We are God's Chosen People."
What's wrong with this? Several things:
* So why doesn't he look after you a bit better? How many of his followers have suffered or died recently? Statistically, are you any better off than followers of other religions?
* Again, the same claim is made by other religions. How do I know they aren't the Chosen Ones?
* So what are the rest of us here for? What about the ones living in remote villages who will live their entire lives without even hearing of your god?
"If the probability of something happening is less than about 1e-15 (or 0.000000000000001) it is considered to be impossible. The probability of life occuring 'by accident' is far less than this, therefore it must be a miracle caused by God.."
What's wrong with this? Several things:
* It ignores the size of the universe. There are hundreds of billions of galaxies, each with hundreds of billions of stars, any of which might have planets capable of supporting life. Even an "impossibly improbable" event is almost a certainty (and we already know of one planet that supports life).