Fine tuned universe: If our planet was even a few degrees closer to the sun, we'd burn. If we were a few degrees further, we'd freeze. If gravity on the sun wasn't exactly as it is, we would either burn or freeze. If the balance of bacteria in our world was tipped off slightly, we would die. There are many examples of how even little chnges in our universe would render earth inhabitable.

Multiverse: Some people argue that because we live in a multiverse with millions of planets, of course the big bang create at least one that can sustain us. But if anyone looks up 'Biosphere 2', you'll find that scientists tried creating their own self-sustaining world on a span of 3.15 acres in Arizona. They spent years creating the completely air-tight building. The most brilliant minds spent seven years and $200 million dollars designing this habitat, and yet it didn't even support life for two years. Sixteen months after it was completed they had to start pumping oxygen in because it couldn't be maintained. Many animals died while ones in the wild thrived. A large part of this failure was simply due to incorrect levels of certain bacterias. If the most intelegant life forms on the planet couldn't create  a self-sustaining world, how could one just simply pop into existance already perfect? And, what are the chances of there always being exactly the right balance of bacterias even while natural selection is taking its course?

The time-frame: One thing that really ties the proof of how fine tuned the earth is, with the impossibility of the earth being old enough for evolution to have occured, is the the sun. If the universe was billions of years old, the sun would've run out of fuel by now. And even if it had enough fuel to last billions of years the sun would have had to have been much larger at first, and our planet would've burned up.

As always, please let me know if there's anything here I haven't covered.