Group size and secular endogamy among the religiously unaffiliated in Canada.

High religious intermarriage among the religiously unaffiliated is usually interpreted as evidence of religion's minor importance for this group. Between 1981 and 2011, religious intermarriage among the unaffiliated in Canada declined from 38 percent to 21 percent, while the unaffiliated population tripled from 7 percent to 23 percent. This paper examines the role of demographic factors such as increased group size in decreased religious intermarriage among the unaffiliated. Using census and survey data, we estimate probit models of religious intermarriage for unaffiliated men and women. The models include individual and group-level characteristics. Results show that for both sexes, relative group size was the single largest contributor to decreased intermarriage. Increased group size allowed the expression of endogamous or within-group marital preferences among the unaffiliated. This secular endogamy, or preference for within-group marriage among the unaffiliated, represents an increasingly important form of religion-related marriage as the unaffiliated population grows. [ABSTRACT FROM AUTHOR]