The argument against the existance of God is that his existance can't be proved using experiments which produce consistant results. Possible results are all-encompasing, and therefore aren't real experiments, which leads scientists to believe God to be "made up" as his nature isn't testable. However, that doesn't prove God doesn't exist.
In a recent video I watched of a Q&A with Richard Dawkins, someone said to him:
"The problem is that you're applying natural laws to God, when He claims to exist outside of them."
Dawkins' response was: "Well that's awfully convenient, isn't it?"
While Dawkins is suggesting that the inability to apply natural laws to God's existance is ultimately evidence of his non-existance, that is not necissarily the case. It's just a fairly typical humanistic stance to take when faced with questions that don't fit in with our current understanding. It's just as convenient to ridicule an avenue of possibility simply because you find another more appealing (and in Dawkin's case, I'd suggest "comforting", but that's another discussion...).
Here's an example:
The rules of this universe are as follows: There are three school boys - Billy, Timmy and Freddy. Billy's mum and dad work overseas, and so Billy has to talk to them on the phone. Timmy and Freddy have never seen Billy's mum and dad, and so don't believe he has parents. Billy can talk to his mum and dad on the phone, but they screen their calls and will only answer phone calls from his home phone. Timmy and Freddy can't go to Billy's house, because they told their parents that Billy lives on his own, and thus are not allowed. Obviously Timmy and Freddy are school children, and can't travel overseas to verify Billy's parents existance. For the purpose of this experiment, the boys' universe is their town.
Timmy says to Billy: "You don't have parents Billy. I've never seen them."
Billy: "Yes I do. I talk to them every night, and they talk to me. Just only on the phone. But they send me presents and stuff."
Timmy: OK then, ask them to send you a scooter. Then I'll know that they're real.
Billy goes home, asks his parents for a scooter. They send one.
Billy: See, I have a scooter. My parents are real.
Timmy: No, see, that could have been a coincidence. You might have already had a scooter, or maybe you went out and bought one, or maybe another one of our friends sent it to you. Hang on a sec. (turns to Freddy) Freddy! Come here!
Timmy: Billy says he has parents, but I don't believe him. I got him to ask them for a scooter, and he got one, but now I need you to verify my findings. Get him to ask for something.
Freddy: OK... Um... Billy - ask your parents for a soccer ball.
Billy goes home, asks his parents for a soccer ball. His parents say no, as sometimes parents do.
Billy: My parents said no.
Timmy: No they didn't. They don't exist. You're just pretending they're real. You didn't get a soccer ball, so they're not real.
Timmy doesn't believe Billy, because Billy's parents exist outside of the confines of Timmy's explainable universe. This is a simplified analogy of why the science vs. religion argument will never be resolved. Science likes problems with mutually exclusive answers. You have to find an experiment that will either come back positive or negative. This doesn't work with God, as he doesn't necissarily choose to respond the way we want him to, and in particular he's not so big on being tested. Imagine if Billy's parents were getting calls from Billy every night asking them to provide evidence of their existance? What's important to Billy's parents here? Meaningful conversation with their son, or the belief of his friends? I'm going with option one. God isn't really into satisfying sceptics, and while sceptics will say that's evidence of his non-existance, logically that doesn't work. If I choose not to answer a question for you, that doesn't mean I don't have an answer.
I'm going to take this one step further - I don't think it's the place of science to be suggesting that it can answer these kind of questions. Science might be able to tell me that sometimes my wife acts in a way I find irrational because of her hormones, it can't tell me the right thing to say to make her feel better every time. It's just not a "science" question. In the same way, science can make observations about the laws the govern the universe, but it can't answer the question of why they did, do, and will behave that way. It's just the way it is, and that's as far as it can go.
This is why I think it's important to recognise the growing number of faith-based science adherents who believe that ultimately, science holds all the answers. That our current scientific understanding shows the existance of God to be false. And most scarily of all, that steps should be taken to stop people being allowed to think, speak and act based on a belief in God, as they're "obviously deluded/irrational/unintelligent". The general consensus from the reading I've been doing seems to be that these faith-based science adherents (who would cry out in disgust at being called that, by the way) see people's right to hold a religious belief as a right to believe in something imaginary if that's what you want, but ultimately it IS imaginary, and the law, education, etc. should treat it as such. Well, I'm not up for that. I believe that God is real. Not just in my head, but that he's real in your world, even if you don't believe it. And believe me, I'm starting to get fired up about this. A short read of the forums on www.richarddawkins.com will show there's plenty of support for this idea, and as a Christian, I can see this as a possible threat to my freedom to continue to be a Christian in the way I can today.
Having just watched some short video on the above mentioned site, I'd like to prove the existance of what I describe as faith-based science adherants with the following quote from Richard Dawkins himself:
It is, of course, a very difficult question to ask how things began at the very beginning of the universe. It's very difficult to even know what the word 'beginning' even means with respect to the universe, that any scientist, any biologist, any reasonable person would accept. However, when you ask what is the
alternative - if the alternative that's being offered to what physists now talk about; a big bang, a spontaneous singularity which gave rise to the origin of the universe - if the alternative to that is a divine intelligence; a creator that would have to have been complicated, statistically improbable, the very kind of thing which scientific theory such as Darwin's exists to explain, then immediately we see that however difficult and apparently inadequate the theory of the physist is, the theory of the theologians; that the first cause was a complicated intelligence, is even more difficult to accept. They're both difficult. But the theory of the cosmic intelligence is even worse.
Well, Dick, that's your opinion. And that's just the thing - it's just opinion. Not science. But because it's a scientist's opinion, that makes it gospel in the church of faith-based science. Believing in the unprovable option you find most easy to rationalise is as much faith as believing in the one that you persieve offers the least rationalisation, but is the most universally applicable solution (which is why it's seen as being "convenient"). You want to believe that something sprang from nothing, even though it flies in the face of the rest of accepted scientific theory? Go ahead. I guess we'll all either see for ourselves or not exist in the end.