Since this is no more than a quote from the bible (Psalm 14:1), it can’t actually be called an argument. The bible, after all, contains claims, not the evidence for those claims; which is why biblical arguments are circular in nature. Nevertheless, since this quote does come up a lot – and is an attempt to affirm the existence of god by discrediting nonbelievers – it might be worth addressing. Interestingly, this quote actually reveals that there have always been those who did not believe in supernatural deities (something that should rather encourage non believers), and that the religious have always felt threatened by them. The entire verse actually goes like this: “The fool hath said in his heart, There is no God. They are corrupt, they have done abominable works, there is none that doeth good”. One way of taking this quote is as an anecdotal description of a single case where some Iron Aged nonbelievers were corrupt, abominable and no good – in which case, it’s objectively irrelevant to us today. But another way of looking at it is as an objective claim about non believers in general – past and present – in which case, we have mountains of evidence to the contrary. Not only are some of the least religious countries in the world also the least corrupt, most prosperous, most generous and most humane, but the vast majority of the world’s top scientists (not exactly fools) do not believe in god. Therefore, anyone who wants to raise this quote, must contend with irrelevance in the former case, or utter falsehood in the latter.
However, since, as I mentioned, this isn’t actually an argument, there’s no real reason to take the high-road with it. Indeed, it’s often the case that by aiming low, you’re more likely to hit the rather lowbrow individuals that advance this biblical claim. In this regard, one ironic way of responding to this quote is by asking if even fools know there’s no god, what’s your excuse? You can also counter by stating that the fool has said in his heart, there is a god. If you get called out on simply coming up with this, inform your counterpart that someone else simply came up with the original version, so there’s no logical difference between the two. And while we’re on the subject, go ahead and ask your counterpart who came up with this idea in the first place, and how they came up with it? Just because it’s written down, doesn’t mean it must be true. Many people with extreme beliefs consider all non-believers to be foolish, but this doesn’t mean we have to take them seriously – not if they don’t make a logical argument. Many Muslims consider all non Muslims to be fools. Ancient Greeks invented the word Barbarian to pejoratively describe foolish outsiders. Ancient Greeks could just as easily (and probably did) entertain the notion that the fool has said in his heart there is no Zeus, but this doesn’t mean we have to take everything they said seriously, does it?