Pardon my words, those of you who love Chesterton--and I do like some of his proverbial statements quite a bit--but I find this comment of his very offensive and very untrue.
I am not an atheist, but I have atheist friends who I have loved dearly and are like family to me. Just because one does not believe in Chesterton's Catholic notions of God (and they are very limited to Catholicism) doesn't make them more likely a fool who will fall for other things.
On the contrary, a house built on reason is a house where the owner knows where all the nails are holding his structure together. A house built merely on faith is one where the owner believes there are nails, even where there may not be.
Now to be fair, being atheist doesn't prevent people from being stupid anymore than being religious guarantees that a person will be just and good. Being Jewish there are many of my family members who hold on to and practice superstitions, even those beliefs that Jews are supposed to avoid, and it rubs me the wrong way. Living in a predominantly Catholic neighborhood growing up I can also list all the ridiculous things that many of these theists believed--knock on wood as I toss some salt over my shoulder. ;)
I know atheists who believe in UFOs (and I means "little green men"), Bigfoot, ghosts, and more. These are very rational people too. But nodody's perfect or immune from choosing to believe in things others think aren't real.
Having an ideology, taking ownership of a creed, siding with a philosophy, and even joining the Catholic Church or the Jehovah's Witnesses does not prevent people from failing to live up to their own standards that they make claim to. Belonging to the ethnic group that invented the God that Chesterton claimed to worship does not prevent my people from thinking and doing foolish things. Being able to quote the Ten Commandments and the Sh'ma in Hebrew doesn't prevent me from committing adultery, coveting, and worshipping idols.
Chesterton has written many clever things (my favorite line of his I like: Being found in a church every Sunday does not make one a Christian anymore than standing in a garage makes one a car.) But alas, sayings are not the same as axioms based on reality.
No ideological or belief system, religion included, is an automatic preventative from being a fool, stupid, and outright wrong. Neither is being an atheist mean you have created a void that trolls, the Loch Ness monster, and Yetis must now fill because God is not there.