For thousands of years, people have observed the world, and concluded that God must have created humans. One of the strongest arguments -- quite rightly -- is that you can't get the complexity of a human being just by random chance. As Hoyle said,
The chance that higher life forms might have emerged in this way is comparable to the chance that a tornado sweeping through a junkyard might assemble a Boeing 747 from the materials therein.That intuition is exactly right. And you don't solve it just by saying "it takes a lot of time". Yes, millions or billions of years is a far longer time than most people can comfortably think about ... but just having lots and lots of tornadoes still doesn't get you a 747 from the junkyard.
You need something, besides just random chance, to get the complexity of modern life. And it's traditional to call that something, "God". As Yudkowsky has noted
The Shaper of Life is not itself a creature. [It] is bodiless [...]. Omnipresent in Nature, immanent in the fall of every leaf. Vast as a planet's surface. Billions of years old. Itself unmade, arising naturally from the structure of physics.
Of course, some guesses (or wishes and hopes and dreams) about the nature of God turned out not to be true. Man was not made in God's image. The universe was not made "for" humans. Humans are not the purpose of God's creation. In fact, God doesn't really have a "purpose", as such. Most important, God doesn't care about humans, and God is not benevolent.
But make no mistake: God is there. A powerful force, designing all life that we see around us. After thousands of years of searching, God was found. Darwin found it. Alas, most religious folks were unable to -- or refused to -- recognize God when it was found.