Inventory of Religious Belief

Abstract

The Inventory of Religious Belief (IRB), developed by Daniel G. Brown and Warner L. Lowe (1951), is a classic 15-item self-report psychometric instrument designed to assess an individual’s cognitive adherence to traditional, orthodox Christian dogma versus theological liberalism and secular nonbelief. Rooted in the post-World War II empirical tradition of the psychology of religion, the IRB operationalizes Christian identity specifically along the dimension of doctrinal assent. The inventory employs a 5-point Likert-type response format, spanning from “Strongly Agree” (1) to “Strongly Disagree” (5). Structurally, the instrument consists of 8 items phrased in a traditional, conservative theological direction and 7 items phrased in a liberal or non-orthodox direction, thereby balancing item valence and mitigating acquiescence response bias. Following reverse-scoring of liberal items, total scores range from 15 to 75, where higher scores signify greater adherence to conservative Christian orthodoxy and a hypothetical midpoint of 45 represents theological neutrality or uncertainty.

Psychometrically, the IRB demonstrates robust reliability and criterion-related validity. Initial validation across university undergraduate cohorts ($N = 887$) yielded an uncorrected split-half reliability coefficient of .77, which adjusted to .87 using the Spearman-Brown prediction formula. Known-groups construct validation confirmed pronounced discrimination between student groups from a conservative Bible college ($M = 73.8$) and a theological seminary characterized by liberal orientation ($M = 48.6$), with complete absence of distributional overlap. Criterion validity is supported by strong positive correlations with behavioral indices of religious commitment (church attendance, frequency of personal prayer, Scripture reading, and financial tithing) as well as clergy self-placement along the liberal–conservative continuum ($r = .74$; Virkler, 1979). This article offers a comprehensive psychometric review of the IRB, elucidating its theoretical foundations, structural mechanics, normative distributions, and ongoing utility in empirical behavioral research.

Keywords

Inventory of Religious Belief, Christian orthodoxy, religious fundamentalism, theological conservatism, psychology of religion, psychometrics, religious dogma, split-half reliability, Brown and Lowe, doctrinal orthodoxy

Authors

The Inventory of Religious Belief was originated and standardized by:

• Daniel G. Brown, Ph.D. — Department of Psychology, University of Denver. Dr. Brown was an American psychologist whose early research examined the intersection of religious ideology, socio-emotional adjustment, personality organization, and authoritarian attitudes during the mid-20th century.
• Warner L. Lowe, Ph.D. — Department of Psychology, University of Denver. Dr. Lowe collaborated extensively on empirical investigations evaluating the relationship between psychopathology, personality variables, and personal religious systems in clinical and normative collegiate samples.

Subsequent psychometric expansion, clergy validation, and clinical application were notably conducted by Henry A. Virkler, Ph.D. (Professor of Psychology, Psychological Studies Institute / Palm Beach Atlantic University), whose empirical investigations (1979, 1980) confirmed the instrument’s discriminant fidelity among ordained ecclesiastical professionals.

Purpose

The primary purpose of the Inventory of Religious Belief (IRB) is to provide an objective, standardized, and quantitatively rigorous assessment of an individual’s cognitive endorsement of classical Christian theological doctrine. During the formative years of empirical psychological measurement, researchers frequently confounded religious sentiment, institutional membership, socio-cultural conformity, and private devotional behavior into broad, undifferentiated scales. Brown and Lowe (1951) sought to isolate the cognitive and propositional dimension of religiosity—specifically ideological orthodoxy—recognizing that religious identity is multifaceted and that cognitive assent to dogma operates as an autonomous psychometric variable.

The instrument was engineered to address critical gaps in both basic psychological research and applied counseling settings:

• Differentiation of Doctrinal Stance: The IRB captures ideological positioning along the continuum separating fundamentalist/conservative orthodoxy from modernist, liberal, or humanistic conceptualizations. While traditional orthodoxy asserts literal divine inspiration, divine creation distinct from animals, virgin birth, substitutionary atonement, and the literal return of Christ, modern liberal theology frequently reinterprets these doctrines metaphorically or emphasizes universal ethical fraternity. The IRB quantifies these distinct ideological frameworks.
• Personality and Socio-Psychological Research: Developed in the intellectual wake of Adorno, Frenkel-Brunswik, Levinson, and Sanford’s (1950) work on authoritarianism and dogmatism, the IRB enables researchers to examine how theological conservatism correlates with traits such as cognitive rigidity, ethnocentrism, psychological adjustment, neuroticism, and interpersonal empathy.
• Pastoral and Clinical Assessment: In ecclesiastical and Christian clinical psychology contexts, the IRB serves as an evaluative tool to determine the ideological orientation of ministry candidates, seminary students, and pastoral counselors (Virkler, 1979, 1980). By identifying a minister’s or client’s location on the theological spectrum, clinicians and supervisors can anticipate clinical dynamics, values conflicts, and therapeutic approaches regarding guilt, forgiveness, and moral culpability.

Psychological Construct

The construct assessed by the Inventory of Religious Belief is traditional Christian doctrinal orthodoxy (often termed theological conservatism or fundamentalism). Rather than measuring affective devotion (e.g., feelings of divine closeness), mystical experience, or structural institutional participation, the IRB focuses on cognitive assent to propositional truth claims that defined historic Christian creeds and post-Reformation Protestant confessions.

The construct encompasses several foundational theological sub-domains operationalized across its 15 items:

• Bibliology (Inspiration and Authority of Scripture): The belief that the Holy Bible is divinely inspired, historically accurate, and authoritative, contrasted with the modernist view that the Bible is an error-prone human artifact that has historically impeded intellectual and scientific progress (exemplified by Item 2, Item 8, and Item 14).
• Theology Proper and Christology: Affirmation of the classical Trinitarian formulation (God existing as Father, Son, and Holy Spirit; Item 7), the miraculous virgin birth of Jesus Christ (Item 6), the unique divine status of Jesus as superior to any historical moral teacher (Item 10), and the literal, bodily second coming of Christ to earth (Item 15).
• Anthropology and Creation: Rejection of purely naturalistic evolutionary views regarding human origins, affirming instead that humanity was created by special divine act, distinct and elevated above the animal kingdom (Item 3).
• Soteriology and Exclusivism: The doctrine of particularism, asserting that salvation, reconciliation with God, and eternal life are obtainable exclusively through faith in Jesus Christ as Lord and Savior (Item 9 and Item 12), set in opposition to universalist or pluralist views that good will and ethical humanism are sufficient irrespective of Christian faith (Item 1).
• Eschatology and the Afterlife: Cognitive affirmation of metaphysical permanence beyond biological death, including literal post-mortem states of heaven and hell (Item 5 and Item 11).
• Theistic Necessity in Human Well-being: The premise that human fulfillment, ultimate happiness, and societal flourishing are inherently contingent upon belief in God, contrasting with the humanist assertion that individuals can live fully happy and enlightened lives without theistic orientation (Item 4 and Item 13).

Theoretical Framework

The theoretical architecture of the IRB rests at the intersection of psychometric attitude theory and the sociological differentiation of religious systems. Mid-20th-century psychologists such as Gordon Allport, L. L. Thurstone, and early sociologists of religion recognized that religious sentiment is not a uniform monolithic construct. Brown and Lowe conceptualized religious belief within an attitude-scaling paradigm wherein doctrinal propositions elicit affective and cognitive evaluations reflecting an underlying ideological schema.

Theoretically, the scale reflects the historic early-20th-century “Fundamentalist–Modernist Controversy” that polarized Western Protestantism. The fundamentalist paradigm conceptualized faith as cognitive allegiance to unalterable propositional revelations (e.g., Biblical inerrancy, substitutionary atonement, literal miracles). Conversely, theological modernism and secular humanism prioritized experiential spirituality, ethical humanism, historical-critical contextualization of Scripture, and the integration of evolutionary biology. Brown and Lowe’s scale models this dialectic directly: items do not merely measure positive religious affect; they explicitly confront respondents with contested doctrinal bifurcations.

Furthermore, the IRB’s structural balance—pairing conservative formulations with liberal or secular humanist counterparts—was informed by psychometric theories regarding acquiescence bias. By forcing individuals to reject humanistic affirmations (such as Item 13: “I think a person can be happy and enjoy life without believing in God”) to attain a high orthodoxy score, the scale separates true ideological orthodoxy from generalized social desirability or generalized positive answering habits.

Validity

The validity of the Inventory of Religious Belief has been established through content-related, known-groups (criterion), and convergent methodologies across multiple independent investigations.

Content and Face Validity

Initial content validation was conducted by submitting the proposed pool of theological items to the academic dean of an accredited conservative Bible college. The items were evaluated for their theological fidelity to historic Christian confessions and their capacity to represent orthodox dogma without introducing extraneous denominational idiosyncrasies (such as specific liturgical rites or eschatological timelines). The final 15 items were confirmed to reflect central tenets of classical Christian theology.

Known-Groups and Construct Validity

Brown and Lowe (1951) tested the construct validity of the IRB by administering it to two theoretically distinct criterion groups expected to occupy opposing poles of doctrinal endorsement:

• Conservative Bible College Students ($n = 35$): Obtained a mean score of $73.8$ out of a theoretical maximum of $75$.
• Liberal Theological Seminary Students ($n = 21$): Obtained a mean score of $48.6$.

Remarkably, Brown and Lowe reported an absolute separation of score distributions between the two cohorts, with zero overlap in empirical scores. This demonstrated the instrument’s capacity to discriminate between individuals with orthodox fundamentalist convictions and those embracing theological liberalism.

Convergent and Criterion-Related Validity

In the primary normative investigation of 887 university students, Brown and Lowe found that total IRB scores correlated positively and significantly with objective behavioral manifestations of institutional and personal religious practice:

• Frequency of personal prayer
• Frequency of private Scripture reading
• Rate of regular church attendance
• Financial contributions and tithing to religious institutions

Further criterion validity was demonstrated in pastoral samples by Virkler (1979). In a study of 54 active parish ministers across northern and southern United States municipalities, pastors provided self-ratings of their theological orientation along a continuum from highly liberal to highly conservative. Scores on the Inventory of Religious Belief demonstrated a Pearson correlation of $r = .74$ ($p < .001$) with self-identified theological conservatism, confirming the scale’s external validity in adult, professionally credentialed populations.

Reliability

The reliability of the IRB was initially evaluated by Brown and Lowe (1951) using an internal consistency split-half framework. From an initial subsample of 300 university students, 100 protocols were randomly extracted for detailed psychometric calculation.

• Split-Half Reliability: The 15 items were divided into two halves using random allocation. The Pearson product-moment correlation between the half-scale sums was $r = .77$.
• Spearman-Brown Correction: Applying the Spearman-Brown prophecy formula to account for the full 15-item length yielded an estimated internal consistency coefficient of $r_{xx} = .87$.

Subsequent psychometric evaluations across denominational and collegiate cohorts have demonstrated that the scale exhibits minimal error variance. The absence of ambiguous or polysemous phrasing contributes to steady item-total correlations across traditional samples, while the balanced distribution of positive and reverse-scored items counteracts mechanical response sets.

Factor Analysis

Although the original 1951 study predated modern computer-assisted Confirmatory Factor Analysis (CFA), Brown and Lowe conceptualized the scale as a functionally unidimensional index of doctrinal conservatism versus liberalism. Subsequent structural reviews in the psychological measurement of religion have supported the existence of a dominant primary factor, along with secondary sub-dimensions related to item directionality and specific theological topics.

Unidimensional General Orthodoxy Factor

When subjected to Exploratory Factor Analysis (EFA), the majority of the variance across the 15 items is accounted for by a robust single general factor, commonly termed “Biblical/Doctrinal Orthodoxy.” Items tapping fundamental theological dogmas—such as Item 2 (inspiration of Scripture), Item 7 (the Trinity), Item 9 (gospel as the sole path to salvation), and Item 12 (eternal life only through Christ)—load strongly on this central dimension ($> .65$).

Methodological and Topical Factors

Depending on sample heterogeneity, secondary factors occasionally emerge:

• Factor 1: Strict Dogmatic Particularism (Traditional items): Encompassing items reflecting supernatural intervention, bodily return of Christ, virgin birth, and salvation exclusivity.
• Factor 2: Anthropocentric / Humanistic Autonomy (Reversed items): Encompassing items asserting that non-Christians can live fully moral, happy, and enlightened lives without God (e.g., Items 1, 4, 13, and 14). In some factor models, this separates partly as a method effect (reverse-phrased items) and partly as an ideological rejection of total depravity.

Overall, because the primary eigenvalue typically dominates scree plots in conservative and mainstream religious populations, the authors and subsequent researchers recommend using the single composite score (15 to 75) as the primary index of theological conservatism.

Instrument / Measurement Tool

The Inventory of Religious Belief is a brief, pencil-and-paper or digital self-report questionnaire. Its structural characteristics and administration parameters are summarized below:

• Instrument Type: Standardized self-report rating scale
• Target Population: Adolescents and adults (typically university age through older adulthood)
• Administration Time: Approximately 5 to 10 minutes
• Number of Items: 15 items
• Item Valence Distribution:
  • 8 items worded in the traditional / conservative direction (Items 2, 3, 6, 7, 9, 11, 12, 15)
  • 7 items worded in the liberal / non-traditional direction (Items 1, 4, 5, 8, 10, 13, 14)
• Response Format: 5-point Likert scale with options:
  • (1) Strongly agree
  • (2) Agree
  • (3) Not sure
  • (4) Disagree
  • (5) Strongly disagree
• Scoring Guidelines:
  • All items are calibrated so that a higher numerical value corresponds to higher theological conservatism/orthodoxy.
  • Traditional items (2, 3, 6, 7, 9, 11, 12, 15) are scored directly: Strongly Agree = 5, Agree = 4, Not sure = 3, Disagree = 2, Strongly Disagree = 1.
  • Liberal items (1, 4, 5, 8, 10, 13, 14) are reverse scored: Strongly Agree = 1, Agree = 2, Not sure = 3, Disagree = 4, Strongly Disagree = 5.
  • Total score is calculated by summing all 15 item ratings.
  • Score Range: Minimum = 15; Maximum = 75. Theoretical midpoint = 45.
  • Interpretation: Scores substantially above 45 indicate adherence to conservative Christian dogma; scores around 45 reflect ambivalence, theological moderation, or moderate liberal stances; scores substantially below 45 indicate theological liberalism, secularism, or rejection of traditional Christian doctrine.

Normative Reference Data

In the seminal standardization sample of 887 university students (Brown & Lowe, 1951), descriptive norms differentiated across denominational affiliations:

• Total Protestant Background ($n = 622$): Mean = $47.16$, $SD = 12.33$
• Baptist ($n = 38$): Mean = $59.76$, $SD = 10.50$
• Lutheran ($n = 27$): Mean = $53.43$, $SD = 11.82$
• Presbyterian ($n = 70$): Mean = $51.99$, $SD = 11.91$
• Congregational ($n = 21$): Mean = $49.44$, $SD = 11.58$
• Methodist ($n = 126$): Mean = $49.11$, $SD = 10.02$
• Episcopalian ($n = 47$): Mean = $44.82$, $SD = 9.63$
• Catholic Active Church Members ($n = 122$): Mean = $58.20$, $SD = 8.61$
• Catholic Background Non-Members ($n = 44$): Mean = $39.82$, $SD = 8.74$
• Non-Church Members ($n = 209$): Mean = $40.80$, $SD = 10.65$

Permissions & Fee and Test Year

The Inventory of Religious Belief was published in 1951 by Daniel G. Brown and Warner L. Lowe in the Journal of Social Psychology. Because the instrument was published in an academic journal prior to 1964 without independent commercial copyright enforcement or subsequent proprietary restrictions, the scale is generally considered to reside within the public domain for scholarly and academic research purposes.

No licensing fees or formal permissions are required for non-commercial research, academic teaching, or clinical inquiry, provided that appropriate attribution is given to the original authors (Brown & Lowe, 1951). Researchers planning commercial distributions or adaptations within proprietary software should verify terms with the current rights holder of the journal (Taylor & Francis).

References

The following publications document the development, validation, and historical applications of the Inventory of Religious Belief:

• Adorno, T. W., Frenkel-Brunswik, E., Levinson, D. J., & Sanford, R. N. (1950). The authoritarian personality. Harper & Row.
• Brown, D. G., & Lowe, W. L. (1951). Religious beliefs and personality characteristics of college students. The Journal of Social Psychology, 33(1), 103–129. https://doi.org/10.1080/00224545.1951.9921808
• Hill, P. C., & Hood, R. W. (Eds.). (1999). Measures of religiosity. Religious Education Press.
• Virkler, H. A. (1979). Counseling demands, procedures, and preparation of parish ministers: A descriptive study. Journal of Psychology and Theology, 7(4), 271–280. https://doi.org/10.1177/009164717900700406
• Virkler, H. A. (1980). The facilitativeness of parish ministers: A descriptive study. Journal of Psychology and Theology, 8(2), 140–146. https://doi.org/10.1177/009164718000800206

Items of the Scale