How Religious Diversity Changed in EU Countries

Key Takeaways

• Twenty-three of 27 EU member states recorded a higher Religious Diversity Index score in 2020 than in 2010. Four countries recorded lower scores, particularly the Netherlands, the Czech Republic, Cyprus, and Hungary.
• Ireland and Malta recorded the largest gains in the EU. Ireland’s score rose from 1.8 to 3.7. Malta’s score rose from 0.7 to 2.5, crossing two classification levels in a decade.
• The EU-wide shift stems primarily from widespread disaffiliation among Christians, not to the arrival of new religious groups. As Christian majorities shrank, populations spread more evenly, raising diversity scores.
• The Netherlands dropped from the EU’s only “very high” diversity country (7.0 in 2010) to “high” (6.8 in 2020) as its religiously unaffiliated population grew to 54%. The Czech Republic fell from 5.1 to 4.7 for the same reason.
• A high RDI score requires balance across groups. When the religiously unaffiliated become dominant, diversity scores fall, just as they do when any other single group dominates.

Religious Diversity Index Change in EU Countries, 2010 to 2020

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Most EU countries became more religiously diverse between 2010 and 2020. Twenty-three of the 27 EU member states recorded a higher RDI score in 2020 than in 2010. Four countries recorded lower scores. This includes the Netherlands, the Czech Republic, Cyprus, and Hungary.

Ireland and Malta recorded the largest gains in the EU. Ireland’s score rose from 1.8 to 3.7, crossing from the “low” to the “moderate” classification. Malta’s score rose from 0.7 to 2.5, jumping two classification levels from “very low” to “moderate.”

Three EU countries crossed from Moderate to High diversity over the same decade:

• Austria: 3.9 → 5.6
• Sweden: 4.9 → 6.3
• Luxembourg: 4.7 → 5.8

Christian Disaffiliation, Not Immigration, Drove EU Diversity Gains

The EU-wide shift stems primarily from widespread disaffiliation among Christians. RDI scores rose in countries where large Christian majorities shrank, and the religiously unaffiliated population grew. This is because the departure of the dominant group made room for a more even distribution across affiliation categories.

The shift does not require new religious groups to arrive. It only requires the dominant one to shrink.

Ireland’s case shows the pace of that change. Its Christian majority fell by 11 percentage points over the decade, from 92% to 81%. That single shift added 1.9 points to Ireland’s RDI score. No other EU country gained more.

France’s position at the top of the EU ranking reflects the same mechanism at a more advanced stage. Its 2020 population is 46% Christian, 43% religiously unaffiliated, and 9% Muslim. No single group holds a majority. That near-even three-way distribution is the highest level of balance any EU country has reached. It is also what places France as the only European country in the global top 10 on the RDI.

Growing Secularity Can Also Lower the Religious Diversity Score

Not every country that grew more secular became more religiously diverse.

The Netherlands scored 7.0 in 2010. It was the highest score in the EU and the only country classified as “very high” diversity. By 2020, its score fell to 6.8, dropping it into the “high” category. The religiously unaffiliated population grew by 9 percentage points to 54% of the country. As the unaffiliated crossed the majority threshold, the distribution became less even. The diversity score fell.

The Czech Republic followed a similar path. Its score fell from 5.1 in 2010 to 4.7 in 2020. The country has one of the largest religiously unaffiliated populations in the EU. That share continued to grow over the decade.

The pattern these two countries reveal is built into how the index works. A country where the unaffiliated become dominant scores the same as a country where Christians dominate. The concentration in religious populations does not lead to a higher religious diversity. In contrast, it makes the score lower.

The broader EU trend reflects a single driver. As the dominant religious group shrinks, populations spread more evenly, and diversity scores rise. The limit of that process is when the departing group is replaced by another that becomes equally dominant. The Netherlands and the Czech Republic have reached that limit. Most EU countries have not.