Puddles

Isn't it amazing how god made the planet just so, so that we can exist on it? I mean, look at how well the environment is suited to us. We happen to see colors, breathe air, eat food, etc. How could this not be god at work?

How many times have you seen the above argument? I happen to see it quite often, and the many variations on it. I think my favorite response is what Douglas Adams said. He likened this line of thought to a puddle looking at the hole that it is in and claiming that it so perfectly fit the shape of the hole that the hole must have been made to fit the puddle perfectly.

We know, of course, that due to the properties of water that it fits into the hole, and not the other way around. If we were to take that water and place it into a different hole, it would happen to fit that hole as well, regardless of the differences in shape between the holes.

The same can be said of animals on this planet, including humans. The reason that we can see color, breathe air, gain sustenance from food is not because the environment was crafted for us, but because we evolved to survive in the environment in which we live. When oxygen was in short supply in the atmosphere, lifeforms on this planet did not use it. It was a waste product. As oxygen levels built up, mass extinctions happened because the organisms living were literally choking to death on it. As variation and natural selection lead to organisms that could use this oxygen, a balance was established that has persisted to this day (after quite a few imbalanced mass extinction events). We breathe oxygen because our ancestors evolved the ability to do so. There's no reason to posit a god that came down and put oxygen in the atmosphere in order for us to breathe, and in fact, that's contrary to the evidence that we do have.