A point to ponder: What are all of the possible forms that complex life can take? You say that if conditions were different, then life as we know it could not exist. True enough. Isn't it likely that if conditions were different then life as we know it would also be different? Imagine a die with a million sides. If I tell you that I'll give you a hundred dollars if you roll a one, and you roll a one, that's impressive. I might be inclined to think that you cheated, that the die was loaded. If I offer you a prize for any odd number and you win the prize, that's not so amazing. How unlikely an event is in this case depends on two factors. How many possibile outcomes are there(in this case one million) and how many are favorable? (that depends on what numbers we agree to consider winners). In the case of life on our planet, we can't really say how many possible outcomes there might reasonably have been, but I think it's obvious that there must have been an extraordinarily large number of possibilities. Some scientists feel that the chances of life evolving here were 1 in 1. That is, some kind of life was going to form. We could rewind the "tape" so to speak and most likely get something different, but we would get something every time. Sort of like giving you a different amount of money for every number on our one million sided die. You know you'll win, but the prize will be different every time. This still leaves room for a god, if you wish. The argument that someone must have set up the parameters that led to the evolution of life will probably always be around. In our example, where did the die come from anyway? Maybe god made it. But there's absolutely no proof that there's someone divine determining which number comes up.
Likewise we can postulate or intuit the existence of a divine being that got the ball rolling in the universe. And we can probably never absolutely rule out his existence, but so far there's reason to believe that anything other than explainable forces of nature underly what we see around us.
