Religion has significant implications for American society and political life, even though the number of non-religious people is increasing. We are therefore very careful in the way we measure attitudes and behaviors related to religious affiliation.
The decline in religion in the United States as well as many other Western democracies has been a major feature of 21st-century. This decline can be seen in many different ways. Perhaps the most significant is a decrease in the number of people who claim to belong to an organized religion. This measure is sometimes called “religious preference” or “religious identification” instead of affiliation. In any case, this measure refers to the way people answer questions about their religion.
“Our question has evolved over time as the composition of the U.S. population changes and attitudes about religion shift.”
Our general rule that “you are who you say you are” works pretty well with religious affiliation. As they say, the devil is always in the details. Our colleagues have actually written several publications on the way we measure religious membership.
Pew Research Center
