A) Hi, I’d like to tell you about my god.
B) What evidence do you have for the existence of this god?
A) Well, I just believe.
B) Sorry, but personal convictions is not evidence.
A) Well, here, this is the bible. It’s god’s word. Here is my proof. It says god exists.
B) Well here is a Harry Potter book, it says people can fly on broomsticks, how is that any more proof? Until you provide actual, verifiable evidence, I will not believe this claim you are making.
A) Well what about nature? Look around you. Is this not enough proof that there is a god? Look how complex life is!
B) Possible, but unlikely. For centuries science has been showing how things in nature can happen naturally without the need for a supernatural power. Science has a long track record of reversing our notions on how the world works as explained by religion.
A) Well prove god doesn’t exist!
B) I don’t have to. You’re the one postulating the claim that one exists. The burden of proof is on you. Until you provide conclusive evidence to support your claim it cannot be taken seriously.
A) Oh yeah? And who made up those rules?
B) Reality. That is after all what we’re talking about here. You are making a claim about an aspect of reality, namely that in this reality there exists a god. Reality is independent of our wishes, and as such we can test the validity of ideas by examining how the preform in reality.
B) For example, in reality, it is best to assume a claim is not true until you are given conclusive evidence to prove that it is. If you believed every claim before being given evidence you wouldn’t make it very far. If a stranger came up to you and offered you a mysterious liquid, saying it would cure all your ills, would you drink it? No, you’d want some sort of proof that 1) He’s not just some crazy wacko, and 2) that the potion is not poison. If you believed his claim without insisting that he provide evidence to prove it, you could potentially be in serious danger. Reality shows us that the method of disbelief until positive evidence is provided is a valid one.