Keep in mind as you wonder at the precision and complexity of these molecular machines and the operations they perform that there are only two viable explanations for how they came to be. Either blind forces and chance mutations resulted in these amazingly choreographed molecular dances or they were intentionally designed by an intelligent agent: The only reason anyone would opt for the first explanation, in my opinion, is that they've ruled out a priori the possibility of there being an intelligent agent capable of having directed the creation of life. Moreover, the primary reason, perhaps, for ruling out such an agent a priori is the fact that one simply doesn't want such a being to exist.
Philosopher Thomas Nagel provides a clear example of this when he writes the following in his book The Last Word:
I want atheism to be true and am made uneasy by the fact that some of the most intelligent and well-informed people I know are religious believers. It isn't just that I don't believe in God and, naturally, hope that I'm right in my belief. It's that I hope there is no God! I don't want there to be a God; I don't want the universe to be like that.I suspect that most people, believers and non-believers alike, hope that God exists or that he doesn't. What I don't understand is why people like Nagel would hope that he doesn't.