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Didasko Project · Observatory

Sources and methodology

Where each number comes from and what it measures.

Last reviewed:

Criteria

A number about the church is only useful for mission if it is true. That is why all the data in the Observatory follows the same criteria.

  • Primary source whenever possibleCensus, report, official dataset. When the data only reached us through news coverage, that coverage is indicated.
  • Year shownEvery number shows the year it refers to. A 2016 figure is not presented as if it were from today.
  • Estimates markedWhat is our own calculation or a third party's estimate appears with the estimate badge.
  • No source, not usedA number we could not confirm in a reliable source is not used on the site.

Why the numbers sometimes differ

Anyone who compares sources finds different values for the same thing. Almost always the difference lies in what each source counts, not in an error.

  1. Evangelicals in Portugal: 2.1% or 3.5%? The 2021 Census counts only those aged 15 or over who answered the question, which was optional: 186,832 people, 2.1%. Joshua Project and Operation World estimate the population of all ages, including children and attendees who do not declare themselves in the Census, and reach 3% or 3.5%. The AEP speaks of 400 to 500 thousand people reached by the churches, an even broader concept. We use the Census as the main figure and the others as a range.
  2. Non-religious in Portugal: 14.1% or 14%? INE measures the population aged 15 or over; Pew estimates all ages. Both figures are correct, each on its own base. In charts comparing European countries we use Pew, so that all countries are on the same base.
  3. 964 or 2,100 churches? The 964 churches of 2016 were the ones registered by the AEP. The roughly 2,100 places of worship of 2025 include those not formally affiliated. The difference reflects criteria as well as real growth.
  4. How much is "practising"? Pew calls a Christian who attends church (Mass or a service) at least once a month a practising one, and measures the frequency of the whole population. The World Values Survey only asks Catholics whether they go to Mass every week. That is why "36% of the Portuguese attend Mass or a service every month" and "about 20% of Catholics go to Mass every week" do not contradict each other.

Sources on Portugal

INE (Statistics Portugal)

Official

Census 2011 and 2021 · 2011, 2021

What it measures
Declared religion (Catholics, Protestants/evangelicals, no religion), population, age and ageing.
Limits
Religion only for those aged 15 or over. In 2021 the question was optional, and percentages are of respondents. It does not separate evangelical denominations.

Portuguese Evangelical Alliance (AEP)

Sector survey

"Evangelical church in Portugal" reports (2016, 2020, 2023 and 2025) · 2016–2025

What it measures
Average attendance, baptisms, new churches, profile of pastors and new converts, regions most in need.
Limits
Survey answered by leaders (350 in 2023, 509 in 2025): figures self-reported by the churches, only those that responded. Part of the data reached us through the press (DN, 7 Margens, RTP), indicated on each figure. Next edition expected in 2028.

Portuguese Evangelical Alliance (AEP)

Sector survey

Survey of 500 non-evangelicals (2019) · 2019

What it measures
Opinion of non-evangelical Portuguese about Jesus, spirituality and the Bible.
Limits
Known through a published summary (Esperança para a Europa); we did not locate the full report.

Portuguese Catholic University (CEPCEP)

Academic

"Young people, faith and future" survey · 2022

What it measures
Religiosity and practice of 2,480 young people aged 14 to 30.
Limits
Online questionnaire, with possible self-selection bias.

Sources on Europe

Pew Research Center

Research center

"How the Global Religious Landscape Changed From 2010 to 2020" · 2025

What it measures
Christians, non-religious and other religions in 201 countries, in 2010 and 2020. We use the official dataset, with the values by country.
Limits
Estimates for all ages, combining more than 2,700 censuses and surveys. That is why Portugal's figure (14% non-religious) differs slightly from the Census (14.1%, 15+ only).

Pew Research Center

Research center

"Being Christian in Western Europe" · 2018 (2017 data)

What it measures
Practice, belief and identity of 24,599 adults in 15 Western European countries.
Limits
Data from 2017. Does not include Eastern Europe.

Pew Research Center

Research center

"Global Christianity" · 2011

What it measures
Distribution of Christians around the world, 1910 and 2010.
Limits
The 1910 figures are historical reconstructions.

Joshua Project

Missiological database

Country and continent profiles · consulted on 25/09/2026

What it measures
Percentage of evangelicals by country and people groups considered unreached.
Limits
A missiological estimate, not a census: it includes children and attendees, and so it runs above census figures. That is why it always appears with the "estimate" badge.

Operation World

Missiological database

7th edition (2010) and Pray for the World (2015) · 2010

What it measures
Percentage of evangelicals in Europe and by country.
Limits
The continental figure (2.5%) is from the 2010 edition. It serves as an order of magnitude, not as a current figure.

Found a more recent figure?

The numbers are reviewed whenever a new Census, an AEP report or a new study comes out. If you know of a source we should include, get in touch.

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