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Denomination Taxonomy

What It Is

The denomination taxonomy is the classification system that organizes 218K+ churches by their theological tradition, denominational affiliation, and doctrinal family. It consists of three layers:

1. Denominations -- specific affiliations (e.g., "Southern Baptist Convention", "Presbyterian Church (USA)")
2. Families -- broad groupings (e.g., "liturgical", "community", "protestant")
3. Theological Lenses -- doctrinal traditions (e.g., "Reformed", "Pentecostal/Charismatic", "Catholic")

These three layers serve different purposes: denominations are for precise filtering, families are for UI theming and grouping, and theological lenses are for cross-denominational discovery (e.g., "show me all Reformed churches regardless of denomination").

Denominations Table

The denominations table stores the canonical list of denominations recognized by PewSearch:

Column	Type	Purpose
id	UUID	Primary key
name	TEXT	Display name (e.g., "Southern Baptist Convention")
slug	TEXT	URL-safe identifier
family	TEXT	Grouping family (liturgical, community, protestant)
about_text	TEXT	Rich description for denomination detail page
church_count	INT	Number of visible churches with this denomination
display_order	INT	Sort position within family
parent_denomination_id	UUID	Hierarchical parent (e.g., SBC → Baptist)
aliases	TEXT[]	Alternative names and abbreviations

Denomination Detail Pages

Route: /denominations/[slug] File: pewsearch/web/src/app/denominations/[slug]/page.tsx

Each denomination has a detail page showing:

• About text (history, beliefs, distinctives)
• Church count in this denomination
• Browse churches filtered to this denomination
• Related denominations in the same family
• State-by-state breakdown

Denomination Index Page

Route: /denominations File: pewsearch/web/src/app/denominations/page.tsx

Lists all denominations grouped by family, with church counts and links to detail pages.

Family Classification

The family field groups denominations into three broad categories used for UI theming, search grouping, and template selection. The classification logic lives in denomination-labels.ts:

Family: liturgical

Churches with formal, structured worship traditions:

Denominations	Pattern Match
Orthodox (all variants)	Contains "Orthodox"
Roman Catholic	Contains "Catholic"
Episcopal	Contains "Episcopal"
Anglican	Contains "Anglican"
Lutheran (all synods)	Contains "Lutheran"

Characteristics: Liturgical calendar, sacramental theology, vestments, formal order of worship, historical creeds prominent.

Family: community

Non-denominational and independent churches:

Denominations	Pattern Match
Non-denominational	Contains "Non-denominational" or "Nondenominational"
Bible Church	Contains "Bible Church"
Vineyard	Contains "Vineyard"
Calvary Chapel	Contains "Calvary Chapel"
Independent	Contains "Independent" (not "Independent Baptist")
Interdenominational	Contains "Interdenominational"
Community Church	Contains "Community Church" as a standalone string (i.e., not preceded by a specific denominational prefix — avoids false matches on "Baptist Community Church" which should stay in the protestant family)

Characteristics: Contemporary worship, less formal, pastor-led governance, autonomous local church, often avoids denominational labels.

Family: protestant (default)

Everything that does not match liturgical or community:

Denominations	Examples
Baptist (all varieties)	SBC, ABC, Independent Baptist, Missionary Baptist
Methodist	UMC, AME, Free Methodist, Wesleyan
Presbyterian	PCA, PCUSA, OPC, EPC
Pentecostal	Assemblies of God, Church of God, Foursquare
Evangelical	Evangelical Free, Evangelical Covenant
Church of Christ	Churches of Christ, Disciples of Christ
Adventist	Seventh-day Adventist
Holiness	Church of the Nazarene, Salvation Army
Everything else	Default fallback

Family Detection Pseudocode

pseudocode: getDenominationFamily(denomination)
  INPUT: raw denomination string from churches table
  OUTPUT: "liturgical" | "community" | "protestant"

  normalized = denomination.toLowerCase().trim()

  // Check liturgical first (most specific)
  LITURGICAL_PATTERNS = [
    "orthodox", "catholic", "episcopal",
    "anglican", "lutheran"
  ]
  if any pattern in LITURGICAL_PATTERNS matches normalized:
    return "liturgical"

  // Check community
  COMMUNITY_PATTERNS = [
    "non-denominational", "nondenominational",
    "bible church", "vineyard", "calvary chapel",
    "independent" (not "independent baptist"),
    "interdenominational"
  ]
  if any pattern in COMMUNITY_PATTERNS matches normalized:
    return "community"

  // Default to protestant
  return "protestant"

Theological Lenses

The sai_theological_lenses table defines 18 cross-cutting theological traditions that span denominations. A single church can belong to multiple lenses (e.g., a PCA church is both "Reformed" and "Evangelical").

All 18 Lenses

ID	Lens Name	Description	Example Denominations
1	Evangelical	Bible-centered, conversion-focused, Great Commission emphasis	SBC, Evangelical Free, many non-denoms
2	Reformed	Calvinist soteriology, covenant theology, confessional	PCA, OPC, Reformed Baptist, Dutch Reformed
3	Pentecostal/Charismatic	Spiritual gifts active today, tongues, prophecy, healing	Assemblies of God, Foursquare, Vineyard
4	Anabaptist	Pacifism, adult baptism, separation of church and state	Mennonite, Amish, Church of the Brethren
5	Liturgical	Formal worship, liturgical calendar, sacramental	Catholic, Orthodox, Anglican, Lutheran
6	Methodist	Wesleyan theology, sanctification, social holiness	UMC, AME, Free Methodist, Nazarene
7	Orthodox	Eastern Orthodox tradition, church fathers, theosis	Greek Orthodox, Russian Orthodox, OCA
8	Restoration	Restore NT church patterns, no creed but Christ	Churches of Christ, Disciples of Christ
9	Holiness	Entire sanctification, clean living, Wesley-influenced	Church of the Nazarene, Salvation Army, CMA
10	Baptist	Believers baptism, congregational polity, soul competency	SBC, ABC, Independent Baptist
11	Progressive	Social justice emphasis, inclusive theology, LGBTQ+ affirming	UCC, Unitarian Universalist, progressive mainline
12	Catholic	Roman Catholic communion, papal authority, seven sacraments	Roman Catholic, Eastern Catholic
13	Anglican	Via media (Catholic + Reformed), Book of Common Prayer	Episcopal (USA), Anglican Church
14	Adventist	Sabbatarian, second coming emphasis, health message	Seventh-day Adventist
15	Latter-day Saint	Book of Mormon, modern prophets, temple worship	LDS Church, Community of Christ
16	Jehovah's Witness	Nontrinitarian, Kingdom Hall, door-to-door witness	Jehovah's Witnesses
17	Unitarian	Religious pluralism, no creed, individual spiritual path	Unitarian Universalist Association
18	Universal	Cross-tradition, applies to all churches	Used as default/catch-all

Junction Table: church_theological_lenses

The many-to-many relationship between churches and lenses:

Column	Type	Purpose
church_id	UUID	FK to churches
lens_id	INT	FK to sai_theological_lenses
confidence	FLOAT	How confident the assignment is (0-1)
source	TEXT	How assigned: "auto" (ML), "manual", "denomination_map"

Lens Filtering via RPC

Because the junction table can have hundreds of thousands of rows, filtering by lens uses a server-side RPC function instead of a client-side .in() query (which would exceed URL length limits):

pseudocode: search_churches_by_lens(p_lens_id, p_query, p_state, p_denomination, p_limit, p_offset)
  -- Server-side RPC function
  SELECT c.*
  FROM churches c
  INNER JOIN church_theological_lenses ctl ON c.id = ctl.church_id
  WHERE ctl.lens_id = p_lens_id
    AND c.directory_visible = true
    AND c.business_status = 'OPERATIONAL'
    AND (p_query IS NULL OR c.fts @@ websearch_to_tsquery(p_query))
    AND (p_state IS NULL OR c.state_code = p_state)
    AND (p_denomination IS NULL OR c.denomination ILIKE '%' || p_denomination || '%')
  ORDER BY c.reviews_count DESC NULLS LAST
  LIMIT p_limit
  OFFSET p_offset

Denomination Alias Expansion

Many denominations have multiple spellings, abbreviations, and variant names in the raw data:

Canonical Name	Aliases
Southern Baptist Convention	SBC, Southern Baptist, So. Baptist
Presbyterian Church in America	PCA, Presbyterian (PCA)
Assemblies of God	AG, Assembly of God
United Methodist Church	UMC, United Methodist
Church of Jesus Christ of Latter-day Saints	LDS, Mormon, LDS Church
Evangelical Lutheran Church in America	ELCA, Evangelical Lutheran
African Methodist Episcopal	AME, A.M.E.

The get_denomination_values() RPC function returns all aliases for a given denomination name, enabling the search system to match any variant:

pseudocode: get_denomination_values(p_denomination)
  -- Returns all denomination names that are aliases of the input
  SELECT DISTINCT d2.name
  FROM denominations d1
  JOIN denominations d2 ON d1.id = d2.parent_denomination_id
                        OR d2.id = d1.parent_denomination_id
                        OR d1.id = d2.id
  WHERE d1.name ILIKE '%' || p_denomination || '%'
     OR p_denomination = ANY(d1.aliases)

Cross-Product Usage

The denomination taxonomy is not PewSearch-specific. It is shared across all properties:

Product	How It Uses Denominations
PewSearch	Search filtering, detail page badges, denomination landing pages
ChurchWiseAI Voice Agent	Per-church theological tradition in system prompt (prompts.py)
ChurchWiseAI Chatbot	Theological lens for doctrinal responses
Pro Website	Template style selection (liturgical → formal, community → modern)
IllustrateTheWord	Illustration filtering by theological tradition

Theological Lens in Voice Agent Prompts

When a church has a theological lens assigned, the voice agent's system prompt includes it:

"[Church Name] is in the {denomination} tradition, with a {lens_name} theological orientation.
When answering questions about beliefs, worship style, or doctrinal positions,
speak from within this tradition, not about it."

This ensures a Reformed Baptist church's voice agent gives Reformed answers, not generic Christian answers.

State + Denomination Combination Pages

PewSearch generates SEO landing pages for every state + denomination combination with significant church counts:

Route: /directory?state={state}&denomination={denomination}

These pages rank for searches like "Baptist churches in Texas" or "Catholic churches in California". The URL parameters make these pages indexable by search engines while sharing the same directory page component.

Top Denomination by State Query

pseudocode: getTopDenominationsForState(state, limit=10)
  SELECT denomination, COUNT(*) as count
  FROM churches
  WHERE directory_visible = true
    AND business_status = 'OPERATIONAL'
    AND state_code = state
    AND denomination IS NOT NULL
    AND denomination != ''
  GROUP BY denomination
  ORDER BY count DESC
  LIMIT limit

Data Quality Notes

• ~15% missing denominations: Many churches (especially non-denominational) have NULL denomination
• Inconsistent naming: Same denomination appears as "SBC", "Southern Baptist", "Southern Baptist Convention" -- alias expansion mitigates this
• Lens assignment gaps: Not all churches have lens assignments; auto-assignment uses denomination-to-lens mapping
• Deprecated denominations: Some denomination records have zero churches after data cleanup -- they remain in the table for historical reference but are hidden from UI when church_count = 0

See Also

• PewSearch Directory Overview -- parent document
• Search System -- how denomination filters work in search
• Data Quality -- denomination data quality issues
• Voice Agent Prompts -- how lenses shape voice agent personality