I was recently sent a link to a youtube video which consists of a slideshow of Hubble telescope images. The person sending it made the comment that he found the images beautiful, and that beauty was a sign of God's existence to him. I wrote a response to his email, and I've included a lightly edited version of it below.
I found them beautiful as well. But I also find it interesting that, as beautiful as we find those things, they are all completely inimical to human life. Most religions hold that the universe was in some way built for us. In reality, only an infinitesimal layer(like a layer of tissue paper wrapped around a basketball) is not completely hostile to human life. And, given that 75% of the Earth is covered with water, really only 25% of that tiny sliver of environment is somewhat safe for humans. Everywhere else in the universe that we have been able to explore is actively hostile to human life.
This touches on one of the biggest reasons I lost faith. The universe is indifferent, when not hostile, to human life. Christianity requires that we assume that this is a function of sin, that we caused this fallen state. The alternative is that this is simply how the universe operates. I would expect to find evidence of a radical break in the universe if the story of the Fall was true. It's not there. We see a history where mankind exists for a blink of geologic time. And death and destruction are a prevalent constant for all of that time. There is no trace of man when the first mass extinctions occurred. There is no evidence of a time before predation and death. Given the way that life likely evolved, you would not expect it. Primitive protein chains would cannabilize each other, and the process just became more refined as primordial replicators became more resistant.
In essence, it really boils down to a few simple points. Take the Chinese earthquake, for example. What are the possibilities?
1) This is just a natural process, completely indifferent to the devastation wrought on the people.
2) This is caused ultimately by mankind's fall. It is an unnatural, yet in a way automatic, event.
3) This is directly caused by God(or some other supernatural being).
Since we can trace and study the causes, #3 can't be substantiated. It is an outside possibility that this was supernaturally caused, but unless we find evidence of an unnatural event(a miracle, in other words; something that could not happen due to physics, for example), there is no reason to assume it. In addition, it violates the idea of an omnibenificent and omnipotent God.
#2 is implausible, simply because we have plenty of pre-human history that we can examine(geological formations, etc). There was never a time(since the Earth formed) that we don't see evidence of tectonic movement. If humans are the cause, we would expect to see a change in the record, and we don't.
This leaves #1, which also has the advantage of being the simplest explanation, and the one that Occam's Razor would lead us to accept. It doesn't disprove the existence of the supernatural, but it does not rely on unprovable claims to have explanatory power.
But the real kicker for me is the realization that those terrible, destructive forces are the flip side of the coin, so to speak, of the beauty we admire. That Chinese earthquake was the same process that formed the pretty mountains that I admired yesterday. The same plate movement formed the Pacific basin I splashed in and found so enthralling. And this repeated over and over. The grace of the cheetah exists to kill. The leap of the antelope exists to put off death for another day. The majestic orca, so playful with humans, seems to enjoy tormenting it's prey with a shocking brutality. The exploding nebulae that we look at through Hubble is also bathing us with high energy particles which will kill some of us.
I just don't think that the god described by Christianity or Judaism is a good fit to the evidence. When you strip away the anthropomorphic baggage, it just doesn't make sense. And, for me at least, it endows those things of beauty with a certain tragic nobility, knowing that both the viewer and the object are in a way accidents. We are unlikely travelers whose paths touch for a moment. It makes me savor those moments and objects more, knowing that they are not some pale reflection of a greater glorious existence, and I can never count on experiencing them again. This outlook extends to everything. It includes the people I interact with as well, which is why atheism has not lead to nihilism for me. The homeless man on the street is my brother, not because of a supernatural decree, but because we are both the beneficiaries of circumstance, and my stature is no more a function of my worth than his is. And, since we are both sentient beings who face an uncaring universe which will mourn our passing equally, it makes no sense to lord over him in some undeserved haughty manner.