I'm sure we've all heard this argument by theists employing the fine-tuning argument. Are you aware, however, of exactly how much this "little bit" really is? Theists would have us think that the slightest change in the distance would have drastic implications for survivability. But that is actually not the case.
We are probably all familiar with the factoid that the Earth is 93 million miles from the Sun. But this is not a fixed distance, but an average distance. The Earth's orbit around the Sun is not perfectly circular but elliptical. Earth's distance from the Sun varies depending on the time of the year. When the Earth is closest to the Sun in early January (at its Perihelion) it is 91.4 million miles away from it. When the Earth is furthest from the Sun in early July (at its Aphelion) it is 94.5 million miles away from it. So during the course of a year, the Earth's distance from the Sun varies by over 3 million miles!
To put that 3 million miles into perspective, the Moon is a little over 238,000 miles away. Now imagine travelling more than 12 times the distance to the Moon. That great distance is the extent to which Earth's distance from the Sun varies - with minimal affects to the temperature on Earth. Mile for mile, the Earth's tilt actually has greater effect on temperature variation than the planet's distance from the Sun. And we can even go into the very important role that Earth's rotation and atmosphere plays in maintaining habitable temperatures.
Of course, the Earth's distance from the Sun is important. My point is that the notion that this distance is perfectly fine tuned and the slightest change would have dire consequences, is simply not true. There would have to be significant change in distance to make life on Earth impossible. The 3 million mile variance does not even represent the full extent of Earth's habitable zone. I'm willing to bet that if the distance were varied by as much as 6 million miles, life on Earth would still be possible although the temperatures would be less comfortable.