Our lab recently published two papers on religion, so this marks a great opportunity to look at the truly timeless question of whether religion is related to happiness.
For everything presented here, I'm using the World Values Survey (WVS)--a survey that has over 400,000 participants in about 100 countries. Given the large number of participants and the broad number of countries sampled, the World Values Survey gives us some of the best benchmarks for how religious people are, how happy people are, and the link between the two.
Assessing how religious people are is far from easy. Are we asking about people who participate in organized religion? But then what about people who are spiritual or believe in God without necessarily attending Church? There is no good answer to this problem, but the question I think is most encompassing in the WVS asked people "how important is God in your life" on a scale of 1 (not at all important) to 10 (very important). Here's a histogram of how frequently each of the ten possible answers to this question came up in the survey:
What immediately jumps out here is that 10 (very important) was by far the most popular choice. Here's another histogram comparing 10 to everyone else (so 1 through 9).
Indeed, 41% of everyone in the sample said that God is maximally important to their lives. In contrast, about 11% said that God is not at all important in their lives.
What these figures illustrate to us is that God is relevant to the vast majority of the global population. And for a sizable plurality (41%), God is extremely important.
God is relevant, but are people who view God as important to their lives any happier than people who see little importance in God? There's been quite a bit of work on this question with studies varying in size from a hundred or so to mass-scale, global surveys. In general, the findings are that people who believe in God and are religious tend to be somewhat happier. This isn't to say that every religious person is going to be happier than every non-religious person, but it does suggest that on average, this tends to be true--so we could say that if we knew nothing else about two people except for whether they are religious or not, then the religious person is somewhat more likely to be happier than the non-religious person (key word here is LIKELY--you'd have to check with them to find out the reality about these two specific individuals).
Lets look at some data on this in the WVS. One big challenge when doing international studies is that there are a lot of factors that feed into happiness and people use scales very differently. So if we just looked at whether God's importance predicts happiness without taking into account country, then we'd be confounding the effect of religion with a lot of other factors (like GDP, education, culture, etc). So one good way is to examine the relationship within each country. Below is a global map with the relationship between God's Importance and satisfaction with life (proxy for happiness) in each country depicted visually. The deeper the blue, the more POSITIVE the relationship; the deeper the green, the more NEGATIVE the relationship. Countries with no data are depicted as white.
As the figure shows above, there's a lot of blue. What we can glean from this is that in most countries, the relationship is positive between God's importance and life satisfaction.
Here's an interesting nugget though: It's not quite that anyone religious is going to be happier. The effect is biggest really for the most religious.
To see this, we can look at average satisfaction with life for people who scored at each of the 10 levels of God's importance. In these analyses, I've subtracted the average satisfaction of life for people in each person's country to make the effects as unconfounded as possible.
What we see here is that people with values of 2-5 are a bit lower than people with values of 1, and then people with values of 6 through 9 are a bit higher than 1. Where the biggest jump is for people who score 10--which as you will recall is 41% of the global population. It's a "go big or go home" effect :).
We also know that the strength of the relationship between religion and satisfaction with life/happiness isn't uniform across all countries. At least two factors are important. First, people who find God important are going to be especially happier than their non-religious counterparts in highly religious countries. So in other words, its going to be especially positive to be religious when other people around you are also religious. And since most people in the world are religious, we get a lot of positive links between religion/God's importance and satisfaction with life/happiness.
The other factor that's important--and we highlighted this in our new paper--"Uncertainty avoidance moderates the link between faith and subjective well-being around the world"--is how much a culture feels uncomfortable with uncertainty. We found that in nations that are highly avoidant of uncertainty, the effect of God's importance on satisfaction with life and happiness is stronger. This makes sense in that in such nations, religion offers people answers to why the world and Universe are as they are, and thus explaining some of the uncertainty. More uncertainty explained, greater peace of mind for those who are made especially anxious by uncertainty.
Long story short, the data suggests a few take home points. 1) God/religion are still relevant and highly important for most people globally (though this isn't uniformly true with some nations being far more religious than others), 2) there is a somewhat positive relationship between religion and happiness, but it varies depending on one's cultural and social context. Furthermore, we need to remember that happiness is extremely mutli-causal--religion is certainly only one of many factors involved.
One last point for the good scientists out there who hate causal language when you have correlational designs. All the data above is indeed correlational, meaning that from this data alone, its hard to draw causal conclusions. But it should be noted there's been a ton of work on the question of how religion and happiness are related, and from this other work, there's good reason to suspect that religion, faith, and related activities do have a causal effect on happiness.