I believe that there is a basis for atheistic beliefs that makes those beliefs not blind guessing...
Atheists have religion, Void. You are not an atheist. You are a fundamentalist in multiple religions.
There are things we know about ancient humans
Omniscience fallacy.
- they were superstitious and confused by much of the world around them,
Omniscience fallacy. You don't get to speak for anybody but yourself.
which is why they tended to create explanations in the form of gods. We don't see people creating new gods today.
New religions are being created fairly often. You belong to some of them.
You must be having one of your schizophrenic episodes again. There is only one of you.
There's also the claim of the "powers" of gods, all of which go directly against what we know about science/biology/physics/meteorology.
Depends on the god.
They were believed to cause storms and other natural disasters.
Since God created the Earth, he also created the conditions for storms.
'Natural' disasters is only a phrase used by government and insurance companies, to either justify government handouts or to get out of paying an insurance claim.
They were claimed to bring the dead back to life and,
Why do you think this has not happened?
in the specific case of the Christian god, circumvent any number of established laws of physics.
God does not circumvent any theory of science.
Bushes can't burn without specific things happening to the bush.
They certainly can. I've seen it personally (when I lived in the desert). It's called ball lightning. That one lasted several minutes, stuck to a lone sagebrush bush. It made no noise, and simply faded away. The bush was unharmed.
These often appeared around aircraft during WW2, either following or leading the aircraft. In a few cases, it comes through the aircraft window (without breaking it), and floats down the center of the aircraft before either disappearing or exiting through the rear bulkhead. They can pass through doors and bulkheads with no problem.
Since then, aircraft have little wires on their wingtips and sometimes the tailfin as well to discharge any electrical charge that builds up before such a thing can form. They are not always effective, but it does reduce St Elmo's fire, another type of display seen by pilots, especially at night.
The surface of water can't support a human who's walking on it.
It certainly can. I walk on water fairly regularly. I even drive my car on it. You should go see ice fishing sometime as well.
Humans organs don't function after being denied oxygen and blood for hours, much less days.
They certainly can. The most common example is the skin itself (the largest organ in the human body). Hospitals typically store skin for grafting purposes for 1-4 weeks, or even longer if you freeze it.
Yet, to be a Christian, you have to believe those claims along with many more "improbable" claims.
Math error. Failure to declare boundary. Failure to declare randX.
How would god make it possible for a human to walk on top of water?
It's his creation. He can do what He wants with it.
Is the God able to manipulate the atomic structure of water or the density of the human on the fly?
Water is not an atom.
What is the likelihood that such an event could realistically be true?
Math error. Failure to declare boundary. Failure to declare randX.
How would a bush burn without the process of pyrolysis happening?
I just told you.
Those reasons are why it's not just blind guessing. Extraordinary claims require extraordinary evidence and religion doesn't provide anything close to enough evidence for a god.
You can't make any evidence just disappear, Void.