One of the many witty things that Chesterton is supposed to have said has acquired the status of an axiom. It's this: "When a man stops believing in God he doesn't then believe in nothing, he believes in anything."
Now, it turns out this isn't found in Chesterton's works, although there are a couple of quotations from the Father Brown stories that seem to constellate the notion: 'It's the first effect of not believing in God that you lose your common sense.' ['The Oracle of the Dog' (1923)]; 'You hard-shelled materialists were all balanced on the very edge of belief - of belief in almost anything.' ['The Miracle of Moon Crescent' (1924)]
So, not actually Chesterton (I'd like to think he was too clever to say anything so foolish), but regardless of that, this allegedly Chestertonian sentiment has acquired a life of its own. Don DeLillo's Mao II insists that 'when the Old God leaves the world what happens to all the unexpended faith? When the Old God goes they pray to flies and bottletops.' Martin Amis agrees, taking Chesterton's apocryphum to the next level: 'It is not that people will start believing in anything: they will start believing in everything.'
It's not just that this sentiment is wrongheaded (although it is spectacularly wrongheaded: it was, for instance, at the time of the widest spread of Christian belief in European that people believed any old nonsense at all: astrology, witchcraft, tales of men whose heads do grow beneath their shoulders, alchemy, the selling of papal indulgences, that pigs could meaningfully be tried in court on charges of murder, and so on). It's that it functions as one more example of a patricularly malign modern-day mental habit; making oneself comfortable with ridiculous or damaging views by telling oneself 'but the alternative is much worse!' It's a kind of credo-indolence; the more deplorable since it doesn't really take much energy to think through what the alternative probably does entail (not much energy, but the terrible risk that you might then have to abandon your starting position ...) An equivalent example: endorsing the war on terror not out of sadism or idiocy, but because you believe that without such a war Islam would make slaves of you and your daughters. How to counter such an attitude?--except by saying: don't be silly.