Given the fact of human evolution, here is a good question for Christmas: if we last shared a common ancestor with the chimps about 5-6 million years ago, and humans have been gradually emerging through a series of hominid intermediates ever since, then why did Jesus die? The connection of thought here might not be immediately apparent. But behind the question lies about 1,600 years or more of church history.

Augustine, Bishop of Hippo (354–430), whose influence, both brilliant and perverse, continues to the present day, is an informative place to start. Augustine believed that the Adam and Eve of the Genesis text were the progenitors of all humankind. When they disobeyed God and were cast out of the Garden of Eden, their sin was then inherited by all succeeding generations: the doctrine of "original sin". Their disobedience became known as the "Fall" (a word not used in the Bible) and Augustine's doctrine of original sin was soon ratified by successive church councils, the Council of Carthage (418) declaring that human mortality was a consequence of the Fall. The focus of Christ's death on the cross – the Atonement – then became Christ's sacrifice for the sin of Adam, whose disobedience had led to the consequent physical death of all humanity.

If the Augustinian account is correct, then there is clear incompatibility with evolution, in which anatomically modern humans first start appearing in Africa about 200,000 years ago through a process involving countless deaths over thousands of generations.

So do we then just shrug our shoulders and say "well so much the worse for theology – science wins in the end"? Surprisingly, perhaps, the Bible suggests otherwise. The tradition of interpreting the early chapters of Genesis figuratively – as a theological essay, not as science – goes back to two great thinkers from Alexandria: the first-century Jewish philosopher Philo, and the third-century church father Origen. In 248 Origen wrote that Genesis references to Adam are "not so much of one particular individual as of the whole human race". Figurative understandings of the Genesis text have been part of mainstream theology ever since.

The first mention of Adam in the Bible is clearly referring to humankind (Genesis 1:26-27) and the definite article in front of Adam in chapters 2 and 3 – "the man" – suggests a representative man, because in Hebrew the definite article is not used for personal names, with Eve being the representative woman.

The Genesis narrative tells the story of humankind going their way rather than God's way. On the day that Adam and Eve sin, they do not drop dead but proceed to have a big family, albeit now alienated from friendship with God, causing spiritual death. Nowhere does the Bible teach that physical death originates with the sin of Adam, nor that sin is inherited from Adam, as Augustine maintained. But the New Testament does teach that humankind stays true to type – all people sin by their own free will – and Christ dies for the sins of all. Christ is the second Adam who opens up the way back to friendship with God through his sacrifice for sin on the cross. The result is the "at-one-ment" that the first Adam – Everyman – is unable to accomplish by his own efforts.

Evolution's gift is a complex brain that endows humanity with free will, enabling personal moral responsibilities towards our neighbour and towards God. We are not puppets. God's gift at Christmas is forgiveness and new life through Christ for those who realise how far we've fallen from using that free will responsibly.