One classic argument theists use to attempt to debunk evolution is the example of the pile of building blocks. You take a box of plastic blocks, say lego and you shake the box. You continue to shake it. The theists asks you, "How long do I need to shake this box before it will form into a perfect model of a house?" Of course you are going to answer, "That's impossible. Even if you shake that box for a million years, the blocks will never form into a model of a house". The theist then says something along the lines of, "If it's impossible for a house to form by shaking the blocks, how can evolutionists believe that life could evolve into what it is today? Life, which is far more complex than this box of blocks? The chances of shaking a box and producing a house is far more likely than life evolving into what we have today. Therefore life on this planet must have been created, just like a house."
As a Christian, at first, I thought that was a great argument, but over time I came to see it for the feeble and ridiculous analogy it really is. There are two major flaws with this argument:
1) A box of blocks are not organic life forms. They have no ability to grow or mutate, unlike a living organism. So there is no comparison.
2) In the above scenario, the goal is to produce a perfect model of a house. Evolution has no ultimate goal whatsoever. Human life evolved AS A RESULT of the environment, not DESPITE the environment. This is where many creationists slip up. They look at it from completely the wrong angle. I used to do the same.
To really understand evolution, the person who uses the above argument needs to look at their analogy from a different perspective. You shake the pile of blocks and you see what you get. You may find you have the perfect home for some other life form. Perhaps that life form would find it extremely comfortable and they might even marvel at how God created all these piles of plastic blocks especially for them to live in. These block-dwelling creatures will thrive . They may even end up becoming the dominant life form on the planet because of it. This is how evolution works. Those beings which are best suited to their environment are the ones that are going to thrive. All the others will become extinct or will be forced to adapt to suit the environment.
This is how it is for mankind. It is why mankind have turned out the way we are today. It was only inevitable that we would thrive. If the earth's environment had been any different, we probably wouldn't have or we would have evolved into something completely different. Maybe some other type of species might be dominating this planet instead.
I can imagine that somewhere out in this universe there may be a planet completely different to ours where totally different types of creatures thrive. They may even come to our planet and see it as ugly an inhospitable. Oxygen may be toxic to them, water may be like acid. Plants and shrubs may seem like monstrosities. It's true that beauty is in the eye of the beholder. What may be amazing and beautiful to us as humans may not be the same for other life forms. Just imagine a fish trying to live out of water!
Clearly the story of the universe is not about humans and how they got there. It's about a planet and the life forms that sprung up upon it.
So next time you try to calculate the odds of human life evolving to what it is today, Don't. Evolution has no goal, it is not trying to achieve anything. There is no house being built. What we have today is the inevitable outcome due to the "shaking of the plastic blocks".