Date added: 09/08/18

The data in Religious Trends have been compiled from a large number of sources, all of which should be attributed, and presented in the form of articles, tables, charts and maps. This invariably means that there may be inconsistencies of definition and measurement, so please read any reservations which are noted. These are often in the datasets offered as csv downloads rather than the articles.

In Religious Trends, we endeavour to take care not only to explain and define the measures used, but also to offer an appropriate interpretation.  We urge readers of Religious Trends to take similar steps to understand the bases of the measurements and use them accordingly.

Measuring religious adherents

When trying to estimate the numbers of adherents of faith, researchers are faced with several problems. Whether a person should be counted as a follower of a particular religion or denomination will often depend on how that term is defined by the researcher or their client, and that may well follow their theology. The answers found in a census or survey will also depend on how the questions are asked.

There are several characteristics by which a person’s faith, or lack of faith, can be defined:

  • Devotion, that is, those for whom faith is important, which some may argue are the true believers.  However, this is a very personal understanding of faith that can only be counted by directly questioning people through research.
  • Practice, which might be measured by activity such as prayer, study of sacred texts, and attendance at worship meetings.
  • Membership, that is, of religious organisations such as churches.  In past editions of Religious Trends, we have followed the practice of denominations and religious groups in the way they count their closest followers.  In the UK, most of the free churches maintain membership rolls; the Church of England has the Electoral Roll; the Roman Catholic Church counts attendees at Mass.  However, since rules and procedures vary according to the differing methods of governance, this is not a consistent measure within the wider Christian Church and across religion as a whole.
  • Profession, that is, by what people say they are.  This group may include large numbers of what are often called nominal followers who will, for example, say they are Christians in answer to a survey but undertake little activity that might be expected of the faithful.
  • Affiliation. There are also many people who do not practice a faith who feel associated with a  religion from their upbringing or social culture. These may include people who are agnostic or even atheist.  Again, they may well say they are, for example, Christians on a census form or in reply to questions in a survey.  This interpretation is widely made of the 2001 UK census data.

A full understanding of religious statistics requires a grasp of the basis behind the count.