Thanks for your topic suggestion, Holly. It’s a major subject about which many books have been written, and I’m afraid I won’t be able to do it justice in a single blog post. The best I can do is to provide some high-level thoughts and point you to some resources for further exploration.
Before delving into your question, I’ll start with the obvious: believers typically would like us to think that the world would be a disaster if everyone were an atheist, while atheists typically assert that the world would be a better place without religion or superstition. It’s like the results of the disputed 2000 U.S. presidential election: if you’re a Democrat, Al Gore got the most votes in Florida, but if you’re a Republican, George W. Bush edged out Gore. The take-away lesson: don’t listen just to the side you prefer; the truth is probably more complex than either side would like you to believe, perhaps even too complex to answer using the tools and information we have available.
It’s not difficult to find examples of atheists (think Stalin or Mao) or believers (think the Ku Klux Klan, the Inquisitors, the Crusaders, or the Taliban) who’ve made the world a worse place. Nor is it difficult to think of skeptics (e.g., Stephen Hawking, Bill Gates, Thomas Edison, Thomas Jefferson) or believers (e.g., Martin Luther King Jr., William Wilberforce, St. Francis of Assisi) who’ve made the world a better place. Nor do we have to look far for dysfunctional religious (e.g., Liberia, Sierra Leone, Somalia, Afghanistan) or nonreligious (e.g., Cambodia under Pol Pot, the Soviet Union, North Korea) nations or for healthy and prosperous religious (e.g., the U.S.A.) or nonreligious (e.g., Sweden, Denmark, Japan) ones.
We should be suspicious of those who make blanket pronouncements about the merits of religion or irreligion based on a selective mining of examples that support one perspective or the other. For example, in The Book That Transforms Nations: The Power of the Bible to Change Any Country, YWAM missionary Loren Cunningham seeks to link every case of a prosperous nonreligious country to some point of Christian influence, past or present, small or great. Even the success of modern Japan is attributed to the work of a Christian industrialist in the early twentieth century. But using this approach, a Muslim apologist could cite Muslim influence as the explanation for the prosperity of any nation. It was, after all, Muslims who reintroduced to medieval Europe classical Greek science and writings, along with important contributions to algebra, medicine, and other disciplines. It serves Cunningham’s agenda to attribute Japan’s success to a Christian industrialist, but not the success of Europe to Muslim or pagan Greek thinkers. The same selectivity pervades many apologists’ explanations for the holocaust: it was all Darwin’s fault, and the antisemtism that had reigned in Germany since the time of the consummate antisemite Martin Luther had nothing to do with it.
Likewise, atheists are quick to trumpet the shining examples of relatively nonreligious countries like those in northern and western Europe and Japan as proof that atheism is good for society, while finding ways to explain away counter-examples like the former Sovient Union, Camboia, Maoist China, and Cambodia (they were due to quasi-religious devotion to a Leader or a political ideology, not to atheism per se, or the atheism was externally imposed, not organic). Though perhaps plausible, this strikes me as a form of special pleading in the service a conclusion reached beforehand (i.e., that atheism is good for society), similar to that of Christian apologists like Cunningham.
I recently received an e-mail message with a call to prayer for Liberia, a country in turmoil that “needs God.” Having spent 15 months as a missionary kid in that country, I was curious to know its current religious situation, so looked it up on Wikipedia:
As a whole, Africa is the continent with the smallest proportion of the nonreligious and unaffiliated; in other words, it is the most religious continent on earth, yet the least prosperous. Perhaps these are not “true” Christians--i.e., the type of Christians who construct a healthy, prosperous society. But then this definition of Christian is too convenient; if “true Christians” are defined as only those who construct a healthy society, then of course all “true Christian” countries are healthy! In any case, it seems we should all be able to agree that religion is not a sufficient condition for a prosperous society.
But even if it’s not a sufficient condition, might it still be a necessary condition? The short answer is No (unless you’re intent on using special pleading to attribute the prosperity of all relatively secular nations to the presence of a mustard seed of Christian influence, past or present, while ignoring the fact that an even greater degree of Christian observance in Liberia has not led to prosperity there). After sociologist Phil Zuckerman lived in irreligious Denmark (where only 18% believe in heaven, compared to 88% of Americans) for a year to study a nonreligious society, he wrote the book Society without God: What the Least Religious Nations Can Tell Us About Contentment, from which I’ll include an excerpt here:
I'd like to end this chapter with a bus ride.
It was a very simple, uneventful bus ride through Aarhus [Denmark], on a relatively unremarkable autumn afternoon. But it was during this particular excursion that I had several personal thoughts and reflections that eventually morphed into the urge and impetus to write this very chapter.
What happened during that bus ride was this: I felt a real sense of goodness. It was a sense of goodness that stemmed not from some internal endorphin rush, but rather, simply from taking in and observing the pleasant social world around me. There I was, heading to an appointment downtown, and I felt it deeply: everything was fine. Calm. Good. The bus was clean - not dirty and grimy, like many buses in large cities can be. The bus was also on time, stopping at each stop right on schedule. And all the people on the bus were sitting peacefully. Teenagers were placidly punching the keypads of their cell phones, old ladies were holding their handbags. A young schoolgirl was absent-mindedly flicking the neon-green strap of her backpack. The bus driver was doing his thing. Outside, through the bus windows, I could see a park full of trees with leaves turning yellow and red. And people jogging. And there was not a honk to be heard, for the flow of traffic was moving right along, smoothly. As we got closer to the city center we passed ice cream stores, book shops, law offices, flower shops, banks, and bakeries. Men and women of all ages buzzed safely alongside the bus on their bikes. The city buildings were largely devoid of graffiti. Litter in the streets was minimal. Every few minutes a pre-recorded voice would announce the name of the upcoming stop. People got off, people got on. Everything was fine. Remarkably fine.
And then, amidst that goodness, I thought about the words of Pat Robertson, particularly his words concerning "Gods wrath," and how when people disobey God, He gets angry, and unleashes His wrath on disobedient nations. Robertson surely isn't the only religious leader who espouses such rhetoric; nearly all religious leaders since time immemorial have warned that when God is disobeyed--or simply ignored--He gets mad, and we all suffer the consequences. Many millions of people, especially in America, sincerely believe this. And yet, on that smooth and uneventful bus ride, there were simply no signs of God's wrath. Just the opposite: all was good. Uneventfully good. Peacefully good. If ever a society could be described as "safe and sound," relatively secular Denmark would be it (pp. 30, 31).
In today’s world, there is a statistically significant correlation between a nation’s lack of religiosity and its societal health, including economic prosperity, longevity, and lowered rates of homicide and other violent crimes, incarceration, and teen pregnancy. Even the abortion rate in secular western and northern Europe is lower than that in the U.S. The suicide rate of the Scandanavian countries is slightly higher than that of the U.S. though interestingly it's lower in the Netherlands, also a notably secular society, so it's difficult to draw any conclusions about suicide rates as they relate to religiosity. I encourage you to read Zuckerman’s book, Society without God, to gain a fuller appreciation of just how well a secular society can function. (He has a new book Faith No More: Why People Reject Religion that I intend to read soon; based on the Kindle preview, I would also heartily recommend it.)
Incidentally, the U.S. stands as somewhat of an anomaly among developed nations in that it is both economically prosperous and relatively religious. Author Greg Paul posits an interesting thesis for this anomaly in his essay, “The Big Religion Questions Finally Solved” (available here; it might take some time to load). He posits that there’s a direct correlation between religiosity and the degree of income inequality of a nation; in other words, the more religious a country is, the greater the disparity between the “haves” and the “have nots,” as in America. The less religious a country is, the fewer very poor and very rich there are. I’m not sure that this correlation Paul has identified is a causal correlation between secularism and relative equality, but it’s an interesting twist worth considering.
I would never claim that freethought (atheism, agnosticism, deism, etc.) is a necessary or sufficient condition for a well-functioning society; there are too many examples to the contrary. But neither would I say the same about religion. There is benign atheism and toxic atheism, benign religion and toxic religion. Neither atheists nor humans are exempt from the foibles of human nature. The worst atrocities in human history have been committed by those most convinced of the rightness of their ideological, utopian causes (whether for this life or the next)--for example, the Crusades, the Catholic-Protestant wars of the 17th century, and the bloodbaths committed by Communists, Nazis, Maoists, and radical Islamists.
I’m sorry I can’t provide a more definitive answer to your question, Holly, but it seems to me that we can’t know for sure whether society would be better or worse if everyone were to become an atheist. Yet the examples of northern Europe and Japan and other secular nations at least assure me that society wouldn’t necessarily go down the toilet, and there’s probably a better than even chance that it would improve, provided that the move toward atheism were voluntary, not externally imposed by tyrants like Stalin or Mao.