This section takes a closer look at religious switching into and out of the religiously unaffiliated category, which consists of people who describe their religion as atheist, agnostic or “nothing in particular.” This group is sometimes referred to as religious “nones.”

Read on for details about where the religiously unaffiliated population has had the largest net gains, what percentage of people raised without a religion are still unaffiliated (i.e., retention rates), which religious groups those who have left the unaffiliated have switched into, and where the religiously unaffiliated population has the largest shares of new entrants (i.e., the highest accession rates).

Of the 36 countries surveyed, 22 have sufficient sample sizes of “nones” to allow analysis of religious switching into and out of the religiously unaffiliated group.

Net gains for the religiously unaffiliated

• In almost every country analyzed, more people have entered the religiously unaffiliated category than have left it.
• Spain has had the largest net gains for the religiously unaffiliated from religious switching.

Remaining religiously unaffiliated

• In many countries, the majority of adults who were raised without a religion are still unaffiliated as adults. This ranges from 63% in Argentina to 92% in Japan.

Leaving the religiously unaffiliated

• In the countries with the largest shares of people leaving the unaffiliated – such as in Argentina – these losses are largely due to people switching to Christianity.
• Some places, such as Singapore, also have seen a small percentage of unaffiliated people switching to Buddhism or Islam.

Entering the religiously unaffiliated

• Italy, Colombia and Greece have the highest levels of “accession,” or entrance, into their religiously unaffiliated populations, with roughly nine-in-ten unaffiliated adults in these countries saying they were raised in a religious tradition. Currently, 23% of Italian and Colombian adults, along with 14% of Greeks, identify as unaffiliated.
• Among those who have switched to become religiously unaffiliated, many were raised Christian.

Where have the religiously unaffiliated experienced the largest net gains from religious switching?

In over half the countries surveyed, more adults say they were raised with a religious affiliation and are now unaffiliated than say they were raised unaffiliated but have since joined a religion. To put it another way, the unaffiliated population has experienced net gains from religious switching.

In Sweden, for example, 52% of adults currently identify as religiously unaffiliated, while just 22% say they were raised without a religion – a difference of 30 percentage points. It results from 32% of all Swedish adults saying they have left their childhood religion and now identify as “nones,” while just 2% of Swedish adults have moved in the opposite direction – from having no religion as children to identifying with a religion as adults.

Even though South Korea has the largest share of adults who have left the ranks of the religiously unaffiliated and taken on a religion (9%), there are far more Koreans who say they were raised in a religion and have since disaffiliated (31%), yielding a 22% net gain for the unaffiliated population among all South Korean adults. 

What percentage of people raised without a religion are still unaffiliated?

In many countries, a sizable majority of adults who say they were raised without a religion remain unaffiliated today, yielding a high retention rate for the unaffiliated population.

Japan, the Netherlands and Sweden have the highest retention rates among the unaffiliated. In each country, at least nine-in-ten adults who were raised religiously unaffiliated still do not identify with a religion.

The lowest retention rates among the religiously unaffiliated are in Singapore, South Korea and Argentina – where about a third or more of people raised without a religion say they now identify with a religion.

Which religious groups have formerly unaffiliated people switched to?

Analyzing retention rates also reveals which religions have been adopted by people who were raised as religiously unaffiliated. In general, among people brought up without a religion who now identify with one, Christianity is the most common choice.

(Read more about entrance rates into Christianity in Chapter 1.)

In a few of the surveyed countries, relatively small shares of people who grew up religiously unaffiliated now identify as Buddhists or Muslims. For example, 6% of Singaporeans who were raised unaffiliated now describe themselves as Buddhists.

Where do the religiously unaffiliated have the largest shares of new entrants?

Most religiously unaffiliated adults surveyed were raised in some religious tradition as children.

In Italy, Colombia and Greece, roughly nine-in-ten adults who now have no religion say they were brought up with some religious affiliation, meaning that the religiously unaffiliated population in those places has a very high “accession” (or entrance) rate.

In these three countries, as well as many others in Europe and the Americas, a large share of religiously unaffiliated adults were raised Christian.

But in Japan, Singapore and South Korea, large shares of today’s religiously unaffiliated population also were raised in religions besides Christianity.

For example, in South Korea, 37% of unaffiliated adults were raised as “nones,” while 33% were raised Christian and 26% were raised Buddhist. In Singapore, nearly a quarter of unaffiliated adults were raised in some religion outside of Christianity or Buddhism, including 17% who say they were raised in a traditional Chinese religion.

Hungary is the only country surveyed in which fewer than around half of all unaffiliated adults were raised with some sort of religion. Unlike its European neighbors, in Hungary only 10% of unaffiliated adults were raised as Christians. This may reflect the legacy of Hungary’s communist period, which lasted from 1949 until 1989.