This is the fourth in an Advent series by Dr Andrew Ollerton.

When I was a boy it's fair to say few things mattered more than the size of my presents. So imagine my horror when on Christmas eve, while rummaging around under the Christmas tree, I discovered the largest present had my sisters name on the label.

Worse still, the tiniest gift was for me. To my shame, under the cover of darkness, by torchlight, I carefully peeled off the labels and swapped them over. Christmas morning dawned. You can imagine the bemused look on faces as I unwrapped a pretty basket of scented soaps and bath salts; while my sister unwrapped the very Swiss Army knife that I so desperately wanted.

It's all too easy over the Christmas season to swap the important stuff for the big, shiny festive stuff and end up disappointed. Today as we turn to John's Gospel, we're reminded that the original Christmas present – wrapped in swaddling cloths and placed in a manger – would have appeared small and insignificant. But in fact it was the greatest of gifts. As the most famous verse in the Bible put it: 'God so loved the world that he gave his one and only Son.'

Now John's Gospel captures the scale of Christmas with a killer opening line: 'In the beginning was the Word.' It echoes Genesis and the opening line of the whole Bible. It's as if John is saying, the arrival of Jesus Christ is a new beginning for this broken world. Christmas is a time to hit 'refresh' and start over.

John's Gospel then draws on the theme of light and darkness: 'The light shines in the darkness, and the darkness has not overcome it.' Though just a small, frail baby, Jesus is the light of the world. As a single candle shatters the darkness, so the light of Christ conquers evil. The prophet Isaiah promised centuries before Christ's birth: 'There shall be no more gloom... for the people walking in darkness have seen a great light. On those living in deep darkness, a light has dawned.' This Christmas, where there is darkness, even deep darkness – anxiety, depression, bereavement – we can call on the name of Jesus and his invincible light.

John then gives the most profound summary of the Christmas story in the whole Bible: 'The Word became flesh and made his dwelling among us' (verse 14). Talk about great things coming in small packages (forget the latest iPhone X) – think about what was contained in the Bethlehem baby. The living Word that called reality into being; the voice that said, 'Let there be light'; the meaning and beauty of the whole cosmos – the Word became flesh. Or as the hymn put it: 'Our God contracted to a span; incomprehensibly made man!'

We call this the doctrine of the incarnation. Carne is Latin for meat or flesh. So Christmas is God in-carne, God in the flesh, dwelling with us. I love how The Message paraphrases this verse: 'God became flesh and blood and moved into the neighbourhood.' Pause for a moment and let the wonder sink in. Within this vast universe there are millions of suns and stars, billions of rocky planets and moons orbiting them. But our planet earth is unique. Not just because it is occupied by us humans, but because it was visited by God.

First Man is a new movie about that famous moment when humans first walked on the moon in 1969: 'One small step for (a) man, one giant leap for mankind.' But amid the euphoric celebrations, Colonel James Irwin, himself an astronaut, made a most perceptive comment: 'The greatest event in human history was not when man walked on the moon. But when God walked on the earth.'

This Christmas, let's not swap the wonder of Christ for mere tinsel and more TV. It may seem bigger and more impressive. But it leaves us as disappointed as a seven-year-old boy with scented soaps and bath salts. Instead, let's put Christ back at the centre of Christmas. One practical way to do this is to gather family and friends in a dark room. Then light a candle and experience the power of light. Read some Scriptures like Isaiah 9 and John 1; put on Handel's Messiah or another worship track and lift up the name of Jesus Christ – the Word who became flesh and made his dwelling among us.

As my favourite carol puts it:

Veiled in flesh the Godhead see,
Hail the incarnate deity.
Pleased as man with man to dwell,
Jesus our Immanuel...

Dr Andrew Ollerton is author of The Bible Course and works with Bible Society. Follow him on Twitter @andyollerton