Protestant churches are experiencing a complex pattern of growth and decline across the world, with Western nations - particularly the UK - emerging as key areas of concern, according to new findings from the Pew Research Center.
The data, drawn from surveys conducted in 24 countries in 2024, highlights how “religious switching” - when someone adopts a different faith from the one they were raised in - continues to reshape Christianity globally.
In the UK, Protestantism has been notably affected by this trend, with more people leaving than joining it.
Pew found that while about 51% of UK adults say they were brought up Protestant, only around 28% continue to identify with the faith as adults.
By contrast, roughly 23% of those raised in the faith say they have moved away from it, while just 3% have joined it as adults.
The UK joins countries such as Sweden and Germany in recording some of the most significant net losses among Protestant populations.
Across the study, former Protestants make up at least 10% of the population in 9 of the 24 countries analysed, underlining the scale of movement away from the tradition.
A key driver behind this shift is the rise in religious disaffiliation.
Many individuals raised in Protestant households are not converting to other Christian traditions or religions but are instead choosing to identify with no religion.
This mirrors a broader pattern seen across Western societies, where secularisation continues to influence religious identity.
“Adults who leave Protestantism tend to become religiously unaffiliated,” said Pew.
Australia reflects a similar trajectory, where 15% of adults are former Protestants who are now religiously unaffiliated, while only around 1% have become Catholic and another 1% have converted to other religions.
Despite these losses, the global picture is not entirely negative for Protestantism.
In several regions, particularly in Latin America, the movement is gaining ground through conversion.
Brazil stands out as a notable example, where 15% of adults have joined Protestantism after being raised outside the faith, compared with 6% who have left it - resulting in a net gain of 9 percentage points.
Most of those switching into Protestant churches in Brazil were previously Catholic.
Overall, Protestantism shows a more balanced global pattern than other Christian traditions, with gains in some regions offsetting declines in others.
In the majority of the countries studied - 16 out of 24 - however, Protestants still make up no more than about 25% of the population.
Only two countries, Ghana (62%) and Kenya (55%), have Protestant majorities.
This relative balance sharply contrasts with developments in Catholicism, which has seen widespread losses due to religious switching across most surveyed countries.
In 12 of the 24 countries studied, a majority of the population was brought up Catholic, with figures varying from 59% in Hungary to as high as 96% in Poland.
While many remain in the Church - 92% of Polish adults, for example, still identify as lifelong Catholics - significant numbers have left.
In fact, former Catholics account for at least 10% of the population in 15 of the countries surveyed, although Catholics still form a majority in 8 of the 24 places studied.
Across the full dataset, Catholicism recorded a net decline through religious switching in 21 of the 24 countries studied.
Italy provides a striking example: 22% of adults report that they were brought up Catholic but currently do not belong to the denomination, while only around 1% were raised outside the Catholic faith but later became part of it.
This results in an overall decline of 21 percentage points linked to religious switching.
Hungary is the exception, being the only country where Catholicism recorded a net gain, with 5% joining the Church compared to 2% leaving.
In Kenya and South Korea, entry and exit levels are roughly equal.
In Europe and parts of Latin America, many Catholics become religiously unaffiliated, joining the growing number of people who describe themselves as atheist, agnostic, or having no particular religion.
Chile illustrates this trend clearly, where nearly one in five adults (19%) were raised Catholic but now describe themselves as having no religious affiliation.
Elsewhere, particularly in countries such as Nigeria, Brazil, Ghana and the Philippines, people who leave Catholicism tend, in many cases, to move into Protestant denominations.
This dynamic has contributed to Protestant growth in those regions.
