There is one word that people commonly mis-define in their colloquial understanding of Darwinism: fittest.
The false understanding of the "survival of the fittest" is that it means "survival of the most ruthless." Kill or be killed. It's a dog eat dog world, after all.
I really do believe that this slanted message is an underlying obstacle to many religious towards evolution. It could be put like this--evolution is mean and bad and therefore is wrong. Basically, if society embraces ruthless evolution, then it will spiral into a more hostile, dangerous place. So, it's rejected outright.
I'll give you two examples taken from a super-dee-duper conservative Christian website:
Darwinian ‘survival of the fittest’ ideas thus powerfully shaped Stalin’s approach to society. Oppression, self glorification, atheism and murder resulted from Stalin’s rejection of his Creator after reading and believing the evolutionary ideas of Darwin. And the most tragic aspect of all? That while Stalin was turning his back on his Creator, he was building his philosophy on a lie.http://www.answersingenesis.org/creation/v10/i4/stalin.asp
Hitler’s understanding of the history of life, and that of Marx, Stalin and Mao, was not devised by a German, Russian or Chinese. It was shaped by an Englishman named Charles Darwin.
Darwin’s book, On the Origin of Species by Means of Natural Selection, Or the Preservation of Favoured Races in the Struggle for Life (1859), laid the groundwork for their worldviews. They each applied the principle of ‘survival of the fittest’ to their own situation.
For Marx and Stalin it was class struggle; for Hitler it was racial struggle. And because Darwinism undermined the authority of the Bible on origins, it meant that, logically, there was no accountability to God for the mass murder they used to implement their ideas. In fact, such tactics could be justified by Darwinism. Without an absolute standard of right and wrong, those in power are not accountable to any standard. So ‘might’ becomes ‘right’.
As Darwin’s evolutionary thinking became widely welcomed and absorbed by society, it not only convinced leaders like Marx and Hitler, but it became a ‘scientific’ framework justifying the public acceptance of their actions for the ‘benefit’ of all humanity.<http://www.answersingenesis.org/creation/v27/i2/darwin.asp>
Conservatives aren't the only one's that have this impression of nature being, "Red in tooth and claw," as Tennyson put it.
In Civilization and Its Discontents, Sigmond Freud took a similar line, arguing that society depends on the renunciation of animal passions and conformity to learned social norms.
In The Self Gene, Richard Dawkins states: "Be warned that if you wish, as I do, to build a society in which individuals cooperate generously and unselfishly towards a common good, you can expect little help from biological nature. Let us try to teach generosity and altruism, because we are born selfish."
In some ways, I don't disagree, but the problem is when 'is' becomes 'ought' or 'ought' becomes 'is.' The Moral Fallacy of science goes like this: "if it's good, it's true" (and conversely, "if it's bad, it's false"). As in, evolution is morally corrupt and therefore false. Another fallacy that we secularists can, on some occasions, be guilty of is the Natural Fallacy--if it's true, then it's right. Example: backstabbing competition is natural in the animal kingdom and therefore acceptable.
The view that we perhaps ought to take is to separate the animal from the genes. Borrowing from the water shed book The Selfish Gene I will elaborate a little with a tiny taste of some the Greek that I learned from seminary, once again, taking advantage of the sometimes descriptive superiority of that sublime language. There are two words that we translate from Greek into English as 'life'--'bios', from which we get 'biology' and 'zoe,' from which comes a really cool chick's name. By doing so I hope to answer the question, "What's the purpose of life?" Well, it depends on which 'life' you're talking about.
Bios-- is all about survival. Genes will do anything they possibly can to replicate. 'Bad' things like rape, cannibalism, incest, murder, infanticide and parasitism. Or, 'good' things like symbiosis, reciprocal altruism, offspring nurture, generosity, etc.
Zoe-- is all about fulfillment. It's not just the existence of life, but the living of life, and its enjoyment and pleasure. It's less about not being dead and more about truly being alive. It's about serving our consciousness rather than being automatons following the commands of our genes.
I hope you'll allow yourself the gift of meditating on the fact that we are the first species that, in a way, can essentially tell our genes to f*&% off. Every other species before us has done one thing with their life--obediently done exactly what their genes tell them to do. We're the first species that can make counter reproduction, and consciously make counter survival choices--like adoption, homosexual partnership, having pets instead of kids, a life devoted to a mission like curing cancer or reducing poverty.
From a 'bios' view pleasure (in all its forms-- base carnal motivated and altruistic conscience motivated) is a means to an ends of successful reproduction. From a 'zoe' view pleasure is an ends in and of itself.
I'll leave you with an application question: are you more about surviving or more about thriving? Genes or consciousness? Replication or fulfillment?