How can you be sure that God doesn't exist?

[Aegon]

Shalom

 Why do you believe that God doesn't exist?
 How can you be sure that God's existence is not real, for certain?
 Humanity has still not uncovered a great deal about our own existence, or what's on the other side of the universe.
 
 If anything, one can only be agnostic, rather than an atheist.
 The logic I am going by is that atheism states that only hard evidence should be used to prove or disprove something; that is after all, the scientific way. Given that there is no evidence to prove or disprove God, you can only be agnostic rather than an atheist.
 For those who don't know what an agnostic is, agnostics are neutral towards the idea; they don't know if God exists or doesn't, and so are open to both possibilites, but conclude that at a human level, is impossible to know the truth.
 
 So anyway, I would like to know why you believe that God doesn't exist?

Everybody has already covered the "Why is God different from anything else in terms of evidence" argument, so I'll go a different route.

The concept of God, especially an Abrahamic one, is incredibly egotistical. The fact that we as humans have such a narrow view of reality as it is, funny enough, I see to be proof against God. Things are far more complex than we could ever dream, and our brains have evolved to survive not discover the true nature of things. Even as a layperson, everything I've learned about the absolutely insane breadth of our universe - from the billions and billions of stars throughout the galaxies to the constant movement of particles on the quantum level - shows that the Judeo-Christian concept of a God is far too simplistic.

A god who just so happens to mirror our behavior, and a hierarchy between man and god that just so happens to mirror our societies... it just all seems very clear to me that this concept of a deity is a primitive concept. The Bible is just Jewish mythology, a story a society created based on its experience in order to explain how things are. It has its merit, and the stories have had their use, but in terms of trying to describe reality...it's on Level 2 or 3, whereas reality as it really is is about Level 40,000. Judaism, Islam, Christianity, they don't even scratch the surface. Does that make sense? It's just not something worth being agnostic about. We're just not that important in the grand scheme of space-time, and Judeo-Christian philosophy pretends we are.

The only religious philosophy that I've studied that has made any sense in regards to reality as we're coming to know it would be Buddhism, for denying the existence of the self, dismissing a supreme deity, and acknowledging the transfer of energy in a closed system as well as emphasizing how our thoughts and actions impact things for generations. All of which make perfect sense... in my humble opinion.