That's not to say there's nothing to worry about and never will be. Asteroids have hit the planet before; this year one missed by less than the distance between Auckland and New York. Then there are dark comets we mightn't even see coming, super volcanoes which could spew enough dust and ash into the atmosphere to block out the sun, solar storms and black holes.
We shouldn't entirely dismiss the notion of the end of the world, or at least the demise of the human race, for two reasons: first, mankind has created the means of its own destruction in the form of nuclear weapons and may be doing so again with global warming; secondly, there are limits to our knowledge.
As the Scottish mathematician J.B.S. Haldane said, the universe may be "not only queerer than we suppose, but queerer than we can suppose".
But to believe that an ancient people could foretell the fate of the planet to the very day represents the triumph of credulousness over rationality. From there it's just a short step to camping out on a mountain in southwest France from which aliens will emerge to bear true believers to safety and a better life beyond the stars.
Recently I was given a journal in which to chronicle my interactions with the human race.
Every second page has a quote from a famous person on the related themes of life being pretty ghastly (Aldous Huxley: "Maybe this world is another planet's hell") because people are pretty ghastly (Jean-Paul Sartre: "Hell is other people.")
Every other page is a blank canvas on which the keeper of the journal can record the names and crimes of those who have spoilt their day.
If the high achievers are to be believed, Homo sapiens is anything but sapient. (Albert Einstein: "Only two things are infinite, the universe and human stupidity, and I'm not sure about the former.")
At times like this you can't help thinking they might have a point.
"Arm the teachers," howled the US gun nuts after the latest mass murder. You have to give them marks for consistency; they have always argued that the problem isn't that there are too many guns, but too few.
Whether parents would be comfortable leaving their children in the care of gunslingers or whether primary school teachers want to become bodyguards aren't questions that concern them.
Others blamed secularism for driving God out of the classroom. That's why, explained a fundamentalist, he didn't intervene to save the 20 infants. God is a gentleman: he doesn't go anywhere without an invitation. (Anton LaVey: "It's too bad that stupidity isn't painful.")
Some of these brainboxes are fond of humanity, but can't abide individual human beings. (Charles Schulz: "I love mankind - it's people I can't stand.") It seems contrary to withhold love from those we know intimately and frequently interact with, while lavishing it on an anonymous mass that includes many individuals from whom we would recoil if we met them in the flesh. Fortunately perhaps, those who profess to love mankind rarely have to practise what they preach.
The notion that charity begins at home seems incompatible with the whole concept of charity, but love does begin at home.
Religion has a lot to answer for in terms of pandering to man's credulity and susceptibility to trading in freedom of thought for blind adherence (Bertrand Russell: "Many people would sooner die than think. In fact, they do"), but Christianity gave us Christmas, for which we should be thankful. Christmas's emotional and spiritual hold and cultural significance derive from its core message of love and family.
Loving family and friends is both a joy and a day-to-day expression of our humanity. It may even be the meaning of life. And who knows? It might make a small contribution to a big picture.
I hope you have a joyful Christmas.
