Evolution, the human soul, and the lower status of animals continue to stir debate not only in philosophy, religion and science, but in politics as well. In 2007 during a debate for the Republican candidate for United States President, three out of the ten candidates raised their hand when asked by the moderator, ‘Is there anyone on the stage who doesn't believe in evolution?’ The possibility of a lineage from animal life to distinctly human life offers the opportunity for a host of objections from some politicians, religious leaders and philosophers alike. Those who express an objection to the theory of evolution take issue with the idea that humanity is merely another link in the chain, albeit the last link. They share a desire to see human life as somehow unique, different, better.

Charles Darwin famously pronounced in The Descent of Man (1871) that the difference between human intelligence and animal intelligence is a matter of ‘degree not kind.’ Yet the Genesis story offers a decidedly different image of humanity's status: God created the world and all its inhabitants and resources for Adam's dominion, calling on Adam to ‘fill the earth and subdue it.’ Those in the Judeo-Christian tradition are invited to see the Earth as little more than humanity's amusement park, with little moral forethought to how we choose to derive pleasure.

Today, many contemporary Christians would like to distinguish themselves from fundamentalist Christians who read the Bible literally, attempting to distance themselves from the message of Genesis by openly accepting scientific theories like evolution that contradict it. If evolution is correct, and life on Earth began microscopically only to diversify and gain complexity and variety, then there was no literal Adam and Eve, but instead generations of Adams and Eves that eventually resulted in the species homo sapien we now know.

Progressive Christians, as we might call them, still embrace their religious faith but recognize when a Biblical story conflicts with established science, scientific truth must be acknowledged. Progressive Christians maintain that Biblical stories aren't to be understood as fact but as mere metaphor, and they see no incongruity in simultaneously believing in a scientific theory like evolution and basic Christian principles.

But are they right? Is it true there exists no incongruity?

I would argue no. Recognizing a scientific theory like evolution makes holding basic Christian principles impossible. In particular, I would argue no Christian can simultaneously maintain a belief in the evolution of the species and the basic Christian principle of the immortality of the human soul. How do I make such a claim?

In order to espouse both views, a Christian must essentially maintain this: the evolutionary process began, branching out, gaining complexity and diversity when God inexplicably intervened in one particular lineage at some arbitrary point and began ensouling one group of living beings with the distinctly immortal soul.

Greek tragedy often employed a plot device known as deus ex machina, Latin for ‘god out of the machine.’ When faced with an inextricable problem, the Greeks were known to solve it by a contrived intervention of some character or device, an ancient equivalent of the superhero saving the day. The distinctly human immortal soul is the quintessential example of deus ex machina. Just like in ancient times, the proposition of a uniquely ensouled human being is fraught with questions throughout: What compelled God to intervene at all? Why intervene with this particular species at some ‘sufficiently human’ point? What made that life form so superior to the life form that came before it to warrant being granted immortal life? And why not just grant all life immortal souls?

Normally, it would not seem fair to hold religious belief up to such philosophical scrutiny but Christians who espouse evolution bring the question upon themselves to explain how such a view is consistent with their faith. It's worth noting that the immortal soul – a life force that continues after physical death – is not a secondary, nonessential belief within Christianity. Arguably, the possibility of enjoying an afterlife with God the Father is the very foundation of Christ's message. To disregard it is to no longer be Christian.

I am left to conclude that no Christian – fundamentalist or not – can reasonably hold a belief in the immortal soul and a belief in the theory of evolution simultaneously. Either they must accept the Genesis story (that humanity was uniquely and purposefully created by God), or that God arbitrarily came upon the scene, intervened in one stage of the evolutionary process and began ensouling a particular life form. Closer inspection reveals these two views actually collapse into one another: the Christian who accepts evolution does essentially believe there existed some first ‘Adam’ and some first ‘Eve’ who were sufficiently in the image of God that He granted them a soul.

If defending this view seems unpalatable to some Christians, it only opens a door (perhaps even Pandora's Box) that Christians usually loathe to consider, namely that there is no difference between the species homo sapien and other animal species. Humanity's status becomes just another animal on Earth living an unremarkable mortal life. This resignation has far-reaching consequences for environmental philosophy and animal ethics with regards to our traditional domination of the planet. The status quo of humanity's special existence becomes harder and harder to defend.

In the end, what this shows is that faith is one thing, but attempting to blend religious faith with established scientific theory is a whole other beast.