It's weird. My argument for my atheism has always went like this:
Me: Do you think there is a secret society of partying teletubbies living under the surface of Pluto?
Other person: No.
Me: Can you prove they're not there?
Other person: No.
Me: Then why don't you believe in their existence?
Other person: Because it's a ridiculous idea.
Me: Bingo!
Now apply the same concept to god.
Anyway, that was always my explanation for my atheism, although people often don't understand it. I don't know why. It's not terribly complex to me. But get this. Recently, I found other people, other atheists are atheists just like me, for the exact same reason. They even use an analogy just like I had. Instead of the secret teletubbies, their analogy is a teapot orbiting the planet.
The logic is, you can't see, observe or infer the likelihood of the existence of a teapot in orbit. So why would you believe it is there in the first place?
That is the basic logic, these people use for their atheism. I learned about it by video googling Richard Dawkins. Those atheists are called "Teapot Atheists." I was a Teapot Atheist all along and never knew it!