In 2005, one Guide to Research described it as a "popular reference"[1]: 462 covering more than 600 periodicals in most major European languages (plus Hebrew and Afrikaans) beginning in 1948.
[2] It covers, "a wide array of periodical literature, including Christian, Jewish, and other world religions and some denominational and popular religious magazines.
"[1]: 463 A guide to how to acquire documents for libraries[3] stated, that Because of the interrelationship between indexing and abstract services and the literature that they document, tools such as Religious and Theological Abstracts (1958-, Myerstown, PA), Religion Index One (1949-, Evanston, IL), and The Catholic Periodical and Literature Index (1930-, Catholic Library Association) often become de facto standards against which many librarians measure their collections.
If a journal is indexed by one of these services, it becomes important on the grounds that the index service provides access points to the information contained in the articles themselves.
[3]: 74 A guide to library research stated that "religion has its primary indexes in Religion Index One, Religion Index Two, Religious and Theological Abstracts, and a few other such titles.