Table of Contents:
- Cover
- Frontispiece
- Half Title Page
- Title Page
- Copyright Page
- Editorial Staff
- Contributing Editors
- Foreword
- Preface to the Revised Edition
- Abbreviations
- Cappella-Abraham
- A Cappella
- Aachen
- Aaron
- Abad Casasempere, Amalia, and Companions, Bb.
- Abandonment, Spiritual
- Abba
- ‘Abbāsids
- Abbelen, Peter
- Abbess
- Abbeville, Claude d'
- Abbo of Fleury, St.
- Abbo of Metz, St.
- Abbot
- Abbot (Canon Law)
- Abbot, Blessing of
- Abbot, Henry, Bl.
- Abbott, Lyman
- Abbreviators
- ‘Abdallāh Zāḫir
- Abdias of Babylon, St.
- Abdinghof, Abbey of
- ‘Abdisho IV (Ebedjesu), Chaldean Patriarch
- ‘Abdisho Bar Berīkā
- Abdisho of Kaskar, St.
- Abduction (Impediment to Marriage)
- Abelard, Peter
- Abell, Thomas, Bl.
- Abercius, Epitaph of
- Abercromby, Robert
- Abgar, Legends of
- Abiding in Christ
- Abingdon, Abbey of
- Abington, Thomas (Habington)
- Abomination of Desolation
- Abondance, Monastery of
- Abortion
- Abortion (Canon Law)
- Abortion (U.S. Law)
- Abrabanel, Isaac (Abravanel)
- Abraham, Patriarch
- Abraham-Act
- Abraham Ecchellensis
- Abraham of Clermont, St.
- Abraham of Ephesus, St.
- Abraham of Sancta Clara
- Abraham the Simple, St.
- Abraham's Bosom
- Abraxas
- Abrunculus of Trier, St.
- Absalon of Lund
- Absolute, The
- Absolutism
- Abstraction
- Absurdity
- Abū ’l-Barakāt
- Abundius of Como, St.
- Acacian Schism
- Acacius of Beroea
- Acacius of Caesarea
- Academic Freedom
- Acca of Hexham, St.
- Acceptants
- Accessus
- Acciaioli
- Accident
- Accolti, Michael
- Accolti, Pietro and Benedetto
- Accusation
- Acedia
- Achard (Aichardus), Bl.
- Achard of Saint-Victor
- Acharius of Noyon, St.
- Acolyte
- Acosta, Gabriel (Uriel)
- Acosta, José de
- Acquaviva
- Acquaviva, Claudius
- Acrostic
- Act
- Act, First
- Act of Settlement, Irish
- Acta-Adam
- Acta Apostolicae Sedis
- Action and Passion
- Action at a Distance
- Action Française
- Active Life, Spiritual
- Activism
- Acton, Charles Januarius
- Acton, John Emerich Edward Dalberg
- Acts, Notional
- Acts of the Apostles
- Acts of the Martyrs
- Acuña, Cristóbal de
- Ad Bestias
- Ad Limina Visit
- Ad Majorem Dei Gloriam (A.M.D.G.)
- Ad Perennis Vitae Fontem
- Ad Regias Agni Dapes
- Ad Sanctam Beati Petri Sedem
- Ad Tuendam Fidem
- Adalar, St.
- Adalard, St.
- Adalbald of Ostrevand, St.
- Adalbero of Augsburg, Bl.
- Adalbero of Metz
- Adalbero of Würzburg, St.
- Adalbert of Bremen
- Adalbert of Prague, St.
- Adalbert the Deacon, St.
- Adaldag, St.
- Adalgar of Bremen, St.
- Adalgis of Novara, St.
- Adalgott, Ss.
- Adam
- Adam, Karl
- Adam Easton
- Adam Marsh
- Adam of Buckfield
- Adam of Ebrach, Bl.
- Adam of Orleton
- Adam of Perseigne
- Adam-Adventists
- Adam of Saint-Victor
- Adam Pulchrae Mulieris
- Adam Wodham
- Adamnan of Iona, St.
- Adams, Henry Brooks
- Adams, John, Bl.
- Addai and Mari, Ss.
- Adela, St.
- Adelaide of Vilich, St.
- Adelard of Bath
- Adelelm of Burgos, St.
- Adelhelm I, Bl.
- Adelphus of Metz, St.
- Adenulf of Anagni
- Adeodatus (Deusdedit) II, Pope
- Adeste Fideles
- Adjutor, St.
- Administrator, Apostolic
- Admont, Abbey of
- Ado of Vienne, St.
- Adonai
- Adoption (in the Bible)
- Adoptionism
- Adoro Te Devote
- Adragna, Antonio Maria
- Adrian, St.
- Adrian I, Pope
- Adrian II, Pope
- Adrian III, Pope, St.
- Adrian IV, Pope
- Adrian V, Pope
- Adrian VI, Pope
- Adrian of Castello (de Corneto)
- Adrianus
- Adso of Montier-en-Der
- Aduarte, Diego Francisco
- Adultery
- Adultery (in the Bible)
- Advent
- Adventists
- Advertence-Aggression
- Advertence
- Advertisements, Book of
- Aelfric Grammaticus
- Aelfric of Canterbury, St.
- Aelfryth of Crowland, St.
- Aelred (Ailred), St.
- Aemilian, Ss.
- Aeon (in the Bible)
- Aeonius of Arles, St.
- Aertnys, Jozef
- Aesculapius, Cult of
- Aesthetics
- Aeterna Caeli Gloria
- Aeterna Christi Munera
- Aeterne Rerum Conditor
- Aeterne Rex Altissime
- Aeterni Patris
- Æthelflæd, Lady of the Mercians
- Aethelred II, King of England
- Affinity
- Affligem, Abbey of
- Afghanistan, The Catholic Church in
- Afra, St.
- African American Catholics in the United States (History of)
- African Missions, Society of
- Afterlife
- Agabus, St.
- Agagianian XV, Gregory Peter
- Agape
- Agape, Ss.
- Agapetus I, Pope, St.
- Agapetus II, Pope
- Agapios of Hierapolis
- Agatha, St.
- Agatho, Pope, St.
- Age (Canon Law)
- Age (Impediment to Marriage)
- Agennētos
- Agent
- Aggression
- Agil-Alabama
- Agil, St.
- Agility
- Agilulf of Cologne, St.
- Agnelli, Giuseppe
- Agnellus of Pisa, Bl.
- Agnes, St.
- Agnes of Assisi, St.
- Agnes of Bohemia, St.
- Agnes of Montepulciano, St.
- Agnes of Poitiers, St.
- Agnosticism
- Agnus Dei
- Agobard of Lyons, St.
- Agostini, Zeferino, Bl.
- Agramunt Riera, Juan, Bl.
- Ágreda, Mary of
- Agricius of Trier, St.
- Agrippa I and II
- Aguado, Pedro de
- Aguilar, Nicolás
- Aguilar Alemán, Rodrigo, St.
- Agustín, Antonio
- Ahern, Barnabas Mary
- Ahikar (Achior)
- Aḥmadiyya
- Ahura Mazda (Ohrmazd) and Ahriman
- Aidan of Lindisfarne, St.
- AIDS
- Aiguani, Michele (Anguani, Angriani)
- Aigulf of Lérins, St.
- Aikenhead, Mary
- Aimeric of Piacenza
- Ain-Traz, Synods of
- Ainay, Abbey of
- Airvault, Monastery of
- Aix, Archdiocese of
- Akathistos
- Akhnaton (Amenhotep IV)
- Akiba Ben Joseph
- Alabama, Catholic Church in
- Alacoque-Albornoz
- Alacoque, Margaret Mary, St.
- Alain (Émile Auguste Chartier)
- Alamanni, Cosmo
- Alan de la Roche
- Alan of Lille
- Alan of Tewkesbury
- Alans
- Alanus Anglicus
- Alaska, Catholic Church in
- Alb
- Alban, St.
- Albani
- Albania, The Catholic Church in
- Albelda, Abbey of
- Alberdingk Thijm, Josephus Albertus
- Albergati, Niccolò, Bl.
- Alberic of Ostia
- Alberic of Rosate
- Alberic of Utrecht, St.
- Alberoni, Giulio
- Albert (Adalbert), Antipope
- Albert, Federico, Bl.
- Albert I of Riga, St.
- Albert II of Riga
- Albert Behaim
- Albert of Jerusalem, St.
- Albert of Pontida, St.
- Albert of Sarteano, Bl.
- Albert of Saxony
- Albert of Trapani, St.
- Albert the Great, St.
- Albertario, Davide
- Alberti, Leandro
- Albertinus of Fonte Avellana, St.
- Alberto Castellani
- Albi, Archdiocese of
- Albigensians
- Albinus (Aubin) of Angers, St.
- Albo, Joseph
- Albornoz, Gil Álvarez Carrillo de
- Albrecht-Alexander
- Albrecht of Brandenburg
- Albrecht of Brandenburg–Ansbach
- Albrechtsberger, Johann Georg
- Albright, Jacob
- Albright, William Foxwell
- Albuin of Säben-Brixen, St.
- Alcalá, University of
- Alchemy
- Alcher of Clairvaux
- Alcobaça, Abbey of
- Alcober Figuera, Juan Tomas, St.
- Alcock, John
- Alcoholics Anonymous
- Alcuin, Bl.
- Aldebert and Clement
- Aldegundis, St.
- Aldeiamento System in Brazil
- Aldemar, St.
- Aldetrude, St.
- Aldhelm, St.
- Aldobrandini
- Aldric of le Mans, St.
- Aldric of Sens, St.
- Alegambe, Philippe
- Alegre, Francisco Javier
- Alemany, Joseph Sadoc
- Alen, John
- Aleni, Giulio
- Alerding, Herman Joseph
- Alès, Adhémar d'
- Alexander, Archibald
- Alexander, Samuel
- Alexander I, Emperor of Russia
- Alexander I, Pope, St.
- Alexander II, Pope
- Alexander III, Pope
- Alexander IV, Pope
- Alexander V, Antipope (Peter of Candia)
- Alexander VI, Pope
- Alexander VII, Pope
- Alexander-Allegri
- Alexander VIII, Pope
- Alexander Neckham
- Alexander Neville
- Alexander Nevski
- Alexander of Abonoteichos
- Alexander of Comana, St.
- Alexander of Fiesole, St.
- Alexander of Hales
- Alexander of Jerusalem, St.
- Alexander, Patriarch of Alexandria, St.
- Alexandre, Noël
- Alexandria
- Alexandria, Diocese of
- Alexandria, Patriarchate of
- Alexandria, School of
- Alexandrian Liturgy
- Alexandrine Bulls
- Alexian Brothers
- Alexius I Comnenus, Byzantine Emperor
- Alexius the Studite, Patriarch of Constantinople
- Alfarabi (Fārābī, Al-)
- Alferius, St.
- Alfield, Thomas, Bl.
- Alfonso de Castro
- Alfonsus, Bonihominis
- Alford, Michael
- Alfred the Great
- Algazel (Ghazzālī, Al-)
- Alger of Liège (Alger of Cluny, Algerus Magister)
- Algeria, The Catholic Church in
- Alhambra, International Order of
- Ali (‘Alī Ibn Abī Tālib)
- Alinsky, Saul David
- Alipius, St.
- All Saints, Solemnity of
- All Souls' Day
- Allamano, Giuseppe, Bl.
- Allegory
- Allegranza, Joseph
- Allegri, Gregorio
- Alleluia-Álvarez
- Alleluia
- Allen, Edward Patrick
- Allen, Frances Margaret, Sister
- Allen, William
- Allouez, Claude Jean
- Alma
- Alma Redemptoris Mater
- Almain, Jacques
- Almería, Martyrs of, Ss.
- Almici, Camillo
- Almond, John, St.
- Alms and Almsgiving (in the Bible)
- Alms and Almsgiving (in the Church)
- Alogoi
- Alonso de Espina
- Aloysius Gonzaga, St.
- Aloysius Rabatá, Bl.
- Alphabetic Psalms
- Alphanus of Salerno, St.
- Alphege of Canterbury, St.
- Alphege of Winchester, St.
- Alphonsus Liguori, St.
- Alpirsbach, Abbey of
- Alt, Albrecht
- Altamirano, Diego Francisco de
- Altaner, Berthold
- Altar in Christian Liturgy
- Altdorf, Abbey of
- Altenburg, Abbey of
- Alternativa
- Altmann of Passau, St.
- Alto, St.
- Altötting, Monastery of
- Alumbrados (Illuminati)
- Alva y Astorga, Pedro de
- Alvarado Cardozo, Laura Evangelista, Bl.
- Álvares, Francisco
- Álvarez, Baltasar
- Álvarez, Diego
- Álvarez de Paz, Diego
- Alvarez-American
- Alvarez Mendoza, Julio, St.
- Álvarez of Córdoba, Bl.
- Alvaro Pelayo
- Alvastra, Abbey of
- Alzog, Johann Baptist
- Amabilis, St.
- Amadeus IX of Savoy, Bl.
- Amadeus of Lausanne, St.
- Amalarius
- Amalberga, Ss.
- Amalric Augerius
- Amalric of Bène
- Amalricians
- Amana Society
- Amandus, St.
- Amandus of Worms, St.
- Amantius of Rodez, St.
- Amat, Thaddeus
- Amator, Ss.
- Amatus of Nusco, St.
- Amatus of Remiremont, St.
- Ambarach, Peter (Mubarach, Benedictus)
- Ambiguity
- Ambition
- Ambo
- Ambrose, St.
- Ambrose of Cahors, St.
- Ambrose Traversari, Bl.
- Ambrosian Chant
- Ambrosian Rite
- Ambrosians
- Ambrosiaster
- Ambrosius Catharinus (Lancelot Politi)
- Ambry (Armarium)
- Amelry, Francis
- Amen
- Amerbach, Veit
- American Academy of Religion
- American Board of Catholic Missions
- American Catholic Historical Association
- American-Anastasius
- American Council of Christian Churches
- American Federation of Catholic Societies
- American Protective Association
- American Schools of Oriental Research
- American Society of Missiology
- Americanism
- Americans United for Separation of Church and State
- Amesha Spenta
- Amette, Léon Adolphe
- Amias, John, Bl.
- Amice
- Amico, Francesco
- Amidism
- Amiens
- Amiot, Jean Joseph Marie
- Amish Churches
- Ammanati de' Piccolomini, Jacopo
- Ammianus, Marcellinus
- Amon
- Amorrites
- Amort, Eusebius
- Amos, Book of
- Amphilochius of Iconium, St.
- Ampleforth, Abbey of
- Ampullae
- Amsdorf, Nikolaus von
- Amyot, Jacques
- Amyraut, Moïse
- An-Xing, Anna, and Companions, Ss.
- Anabaptists
- Anacletus (Cletus), St. Pope
- Anacletus II, Antipope
- Analogy
- Analogy, Theological use of
- Analogy of Faith
- Analysis and Synthesis
- Anamnesis
- Anarchism
- Anastasia, Ss.
- Anastasius, St.
- Anastasius-Andrew
- Anastasius I, Byzantine Emperor
- Anastasius I, St. Pope
- Anastasius II, Pope
- Anastasius III, Pope
- Anastasius IV, Pope
- Anastasius, Patriarch of Constantinople
- Anastasius, Patriarchs of Antioch, Ss.
- Anastasius Sinaita, St.
- Anastasius the Librarian
- Anathema
- Anathemas of Cyril
- Anatolius of Constantinople
- Anatolius of Laodicea, St.
- Anaxagoras
- Ancestor Worship
- Anchieta, José (Joseph) de, Bl.
- Anchin, Abbey of
- Anchor
- Anchorage, Archdiocese of
- Anchorites
- Ancrene Riwle
- Ancyra
- Andechs, Abbey of
- Anderson, Lars (Laurentius Andreae)
- Anderton, Robert, Bl.
- Anderton, Roger and Lawrence
- Andlauer, Modeste, St.
- Andleby, William, Bl.
- Andorra, The Catholic Church in
- Andrade, Antonio de
- André, Bernard Andreas
- Andrew, Apostle, St.
- Andrew Abellon, Bl.
- Andrew Caccioli, Bl.
- Andrew Corsini, St.
- Andrew de Comitibus, Bl.
- Andrew Dotti, Bl.
- Andrew Franchi, Bl.
- Andrew of Crete (of Jerusalem), St.
- Andrew of Fiesole, St.
- Andrew-Anglo
- Andrew of Longjumeau
- Andrew of Peschiera, Bl.
- Andrew of Rinn, Bl.
- Andrew of Saint-Victor
- Andrew of Strumi, Bl.
- Andrew the Catechist, Bl.
- Andrewe, Richard
- Andrewes, Lancelot
- Andrieu, Michel
- Andronicus II Palaeologus, Byzantine Emperor
- Andronicus III Palaeologus, Byzantine Emperor
- Aneiros, León Federico
- Anfredus Gonteri
- Angel of the Lord
- Angela of Foligno, Bl.
- Angelina, St.
- Angelina of Marsciano, Bl.
- Angelo Carletti di Chivasso, Bl.
- Angelo of Acri, Bl.
- Angelology
- Angels
- Angels, Guardian (in the Bible)
- Angels of the Churches
- Angelus
- Angelus Clarenus
- Angelus de Scarpetis, Bl.
- Angelus Silesius
- Anger
- Anger (in the Bible)
- Angers
- Angilbert, St.
- Angilramnus of Metz
- Anglesey, Priory of
- Anglican Communion
- Anglican Orders
- Anglican/Roman Catholic Consultation in the United States (ARC-USA)
- Anglican/Roman Catholic International Commission (ARCIC)
- Anglicanism
- Anglo-Catholics
- Anglo-Saxon Art
- Anglo-Anselm
- Anglo-Saxons
- Angola, The Catholic Church in
- Ani
- Aniane, Abbey of
- Anianus of Chartres, St.
- Anianus (Aignan) of Orléans, St.
- Anianus and Marinus, Ss.
- Anicetus, St. Pope
- Anima Christi
- Anima Naturaliter Christiana
- Animals, Rights of
- Animals, Symbolism of
- Animism
- Annals and Chronicles
- Annates
- Anne of Denmark
- Anne of Jesus, ven.
- Anne of St. Bartholomew, Bl.
- Anne and Joachim, Ss.
- Annecy, Monastery of
- Annibale, Giuseppe d'
- Annihilation
- Annius, John (Nanni)
- Anno of Cologne, St.
- Annuario Pontificio
- Annunciation
- Anointing
- Anointing of the Sick, I: Theology of
- Anointing of the Sick, II: Liturgy of
- Anonymity and Pseudonymity
- Anonymous Christian
- Anonymous of York
- Anovulants (Moral Aspect)
- Ansbald, St.
- Ansbert of Rouen, St.
- Anscombe, Gertrude Elizabeth Margaret
- Anse, Councils of
- Ansegis of Fontenelle, St.
- Anselm II of Lucca, St.
- Anselm of Canterbury, St.
- Anselm-Antipodes
- Anselm of Laon
- Anselm of Liège
- Anselm of Nonantola, St.
- Anselmo Dedicata, Collectio
- Ansfrid, Bl.
- Ansgar, St.
- Anstrudis, St.
- Ansuerus, St.
- Antependium
- Anterus, Pope, St.
- Anthelm of Chignin, St.
- Anthelmi, Joseph
- Anthemius
- Anthimus
- Anthimus of Trebizond
- Anthony, Patriarchs of Constantinople (I-IV)
- Anthony Bonfadini, Bl.
- Anthony Neyrot, Bl.
- Anthony of Egypt, St.
- Anthony of Padua, St.
- Anthony of Stroncone, Bl.
- Anthony of the Holy Ghost
- Anthony Pavonius, Bl.
- Anthropocentrism
- Anthropology, Theological
- Anthropomorphism
- Anthropomorphism (in the Bible)
- Anthropomorphism (In Theology)
- Anthroposophy
- Antichrist
- Anticlericalism
- Antinomy
- Antioch
- Antioch, Patriarchate of
- Antioch, School of
- Antiochene Liturgy
- Antiochus IV Epiphanes
- Antipathy
- Antiphon
- Antipodes
- Antipope-Apostasy
- Antipope
- Antoine, Paul Gabriel
- Antolínez, Agustín
- Antonelli, Giacomo
- Antonia of Florence, Bl.
- Antoniῐ (Alekseῐ Pavlovich Khrapovitskiῐ)
- Antonines (Antonians)
- Antoninus, St.
- Antonius Andreas
- Antonius de Butrio
- Antwerp
- Anunciación, Domingo de la
- Anxiety
- Apamea
- Aparicio, Sebastián de, Bl.
- Aper of Toul, St.
- Aphraates
- Apocalypse, Iconography of
- Apocalyptic
- Apocalyptic Movements
- Apocatastasis
- Apocrisiarius
- Apocrypha
- Apocrypha, Iconography of the
- Apollinarianism
- Apollinaris of Hierapolis, St.
- Apollinaris of Laodicea, The Younger
- Apollinaris of Monte Cassino, St.
- Apollinaris of Valence, St.
- Apollonia of Alexandria, St.
- Apollonius of Tyana
- Apollos
- Apologetics, History of
- Apologies, Liturgical
- Apologists, Greek
- Apophatic Theology
- Apophthegmata Patrum
- Apor, Vilmos, Bl.
- Aporia
- Apostasy
- Apostle-Araújo
- Apostle
- Apostles, Iconography of
- Apostles' Creed
- Apostles of Jesus
- Apostleship of Prayer
- Apostleship of the Sea
- Apostolate and Spiritual Life
- Apostolic
- Apostolic Blessing
- Apostolic Camera
- Apostolic Church Order
- Apostolic Constitution
- Apostolic Constitutions
- Apostolic Delegation in the U.S.
- Apostolic Exhortation
- Apostolic Faith
- Apostolic Fathers
- Apostolic See
- Apostolic Succession
- Apostolicae Curae
- Apostolici
- Apostolici Regiminis
- Apostolicity
- Apotheosis
- Appeal to a Future Council
- Appellants
- Appetite
- Apprehension, Simple
- Appropriation
- Aquileia
- Aquileian Rite
- Aquilinus of Milan, St.
- Aquinas, Philippus
- Arabia
- Arabian Philosophy
- Aramaeans
- Aramaic Language
- Aramaic Language, Biblical
- Arator
- Araújo, Antônio de
- Araújo-Argyros
- Araújo, Francisco de
- Arbela, Chronicle of
- Arbez, Edward Philip
- Arbiol y Diez, Antonio
- Arbogast of Strasbourg, St.
- Arbroath, Abbey of
- Arcadelt, Jakob
- Arcadius, Roman Emperor
- Arcanum
- Archangela Girlani, Bl.
- Archangelo of Calatafimi, Bl.
- Archbishop
- Archchancellor
- Archdeacon
- Archdiocese
- Arche International, L'
- Arches, Court of
- Archiereus
- Archives, Ecclesiastical
- Archives, U.S. Catholic
- Archpriest
- Archpriest Controversy
- Arcimboldi, Giovannangelo
- Arcosolium
- Arcoverde de Albuquerque Cavalcanti, Joaquim
- Ardbraccan, Abbey of
- Ardchattan, Priory of
- Arden, Edward
- Ardenne, Monastery of
- Aredius, St.
- Areopagus
- Arethas, Archbishop of Caesarea
- Arévalo, Rodrigo Sánchez de
- Argenteuil, Abbey of
- Argentina, The Catholic Church in
- Argentré, Charles du Plessis d'
- Argimir, St.
- Argumentation
- Argyropoulos, John
- Argyros, Isaac
- Arialdo-Arnulf
- Arialdo, St.
- Arianism
- Arias, Francis
- Aribo of Mainz
- Aridity, Spiritual
- Arintero, Juan González
- Aristeas, Letter of
- Aristides
- Aristocracy
- Aristotelianism
- Aristotle
- Arius
- Arizona, Catholic Church in
- Ark of the Covenant
- Arkansas, Catholic Church in
- Arlegui, José
- Arles
- Armada, The Spanish
- Armagh, Primatial See of
- Armellini, Mariano
- Armenia, Martyrs of, Bb.
- Armenia, The Catholic Church in
- Armenian Christianity
- Armenian Liturgy
- Armenians, Decree for
- Armentia, Nicolás
- Arminianism
- Arminius, Jacobus
- Arnáiz Barón, Rafael, Bl.
- Arnaldus Amalrici
- Arnauld
- Arnobius the Elder
- Arnobius the Younger
- Arnold, Gottfried
- Arnold of Bonneval (Marmoutier)
- Arnold of Brescia
- Arnold of Hiltensweiler, Bl.
- Arnoldi, Bartholomaeus
- Arnulf of Gap, St.
- Arnulf of Lisieux
- Arnulf-Asperges
- Arnulf of Metz, St.
- Arnulf of Milan
- Arnulf of Soissons, St.
- Arras, Councils of
- Arras, Martyrs of, Bb.
- Arregui, Antonio María
- Arriaga, Pablo José de
- Arriaga, Rodrigo de
- Arricivita, Juan Domingo
- Arrieta, Franciso Sales de
- Arrillaga, Basilio
- Arrowsmith, Edmund, St.
- Arrupe, Pedro
- Ars Moriendi
- Ars Praedicandi
- Arsenius Autorianus, Patriarch of Constantinople
- Art
- Art (Philosophy)
- Art, Early Christian
- Arthurian and Carolingian Legends
- Article of Faith
- Artificial Intelligence
- Artusi, Giovanni Maria
- Arundel, Thomas
- Ås (Asylum), Abbey of
- Asbury, Francis
- Ascellino
- Ascension of Jesus Christ
- Asceticism
- Asceticism (in the New Testament)
- Asceticism (Theological Aspect)
- Aseity (Aseitas)
- Asensio Barroso, Florentino, Bl.
- Ash‘arī, Al-(Abū Al-Ḥasan) ‘Alī
- Ashes, Liturgical use of
- Ashley, Ralph, Bl.
- Asia, Roman Province of
- Asia Minor, Early Church in
- Aske, Robert
- Asperges
- Aspilcueta-Athenagoras
- Aspilcueta, Martin (Doctor Navarrus)
- Assault
- Assemani, Joseph Aloysius
- Assemblies of French Clergy
- Assemblies of God
- Assisi
- Association
- Association of Professors of Missions
- Association of Theological Schools
- Associationism
- Assumption, Religious of the
- Assumption, Sisters of the
- Assumption of Mary
- Assumptionists
- Assumptus-Homo Theology
- Assy, Notre-Dame-de-Toutegrâce
- Assyria
- Assyrian Church of the East
- Astarte
- Asterius of Amasea, St.
- Asterius the Sophist
- Astorch, María Angela, Bl.
- Astrain, Antonio
- Astral Religion
- Astrology
- Astros, Paul Thérèse David d'
- Astruc, Jean
- Asylum, Cities of
- Asylum, Right of
- Athala of Bobbio, St.
- Athanasian Creed
- Athanasius, St.
- Athanasius I, Patriarch of Constantinople
- Athanasius of Naples, St.
- Athanasius the Athonite, St.
- Atheism
- Athelney, Abbey of
- Athelstan, King of England
- Athenagoras
- Athenagoras I
- Athens-Augustinian
- Athens, Schools of
- Atienza, Juan de
- Atkinson, Matthew (Paul of St. Francis)
- Atkinson, Thomas, Bl.
- Atlanta, Archdiocese of
- Atomism
- Atonement
- Atonement, Day of (Yom Kippur)
- Atticus of Constantinople, St.
- Attigny, Councils of
- Attilanus, St.
- Attitudes
- Atto, Collection of
- Atto of Milan
- Atto of Vercelli
- Attrition and Attritionism
- Attwater, Donald
- Atwater, William
- Aubenas, Martyrs of, Bb.
- Aubert of Avranches, St.
- Aubigné, Jean Henri Merle d'
- Aubrac, Order of
- Aubusson, Pierre d'
- Auctor of Metz, St.
- Auctorem Fidei
- Audi Benigne Conditor
- Auger, Edmond
- Augsburg
- Augsburg, Peace of
- Augsburg Confession
- Augury
- Augustine, St.
- Augustine, Rule of St.
- Augustine Kažotić, Bl.
- Augustine Novellus, Bl.
- Augustine (Triumphus) of Ancona
- Augustine of Canterbury, St.
- Augustinian Heritage Institute
- Augustinian Nuns and Sisters
- Augustinian Recollects
- Augustinian-Ave
- Augustinian Spirituality
- Augustinianism
- Augustinianism, Theological School of
- Augustinians
- Augustinis, Aemilio de
- Augustinus
- Aulne-sur-Sambre, Abbey of
- Aunarius of Auxerre, St.
- Aunemund of Lyons, St.
- Auraeus, St.
- Aurea of Córdoba, St.
- Aurelian of Arles, St.
- Aurelian of Réomé
- Aurelius of Armenia, St.
- Aurelius and Sabigotona, Ss.
- Aureole (Nimbus)
- Aurillac, Abbey of
- Aurora Iam Spargit Polum
- Aurora Lucis Rutilat
- Ausculta Fili
- Austin, John
- Australia, The Catholic Church in
- Austreberta, St.
- Austregisilus (Outril), St.
- Austria, The Catholic Church in
- Authority
- Authority, Civil
- Authority, Ecclesiastical
- Auto-da-Fé
- Autocephaly
- Autos Sacramentales
- Autpert, Ambrose, St.
- Autun
- Autun, Councils of
- Auxerre
- Auxilius of Naples
- Avarice
- Avars
- Ave Maria (Antiphon)
- Ave Maris Stella
- Ave-Aztec
- Ave Regina Caelorum
- Ave Verum Corpus
- Avellana Collectio
- Avellino, Andrew, St.
- Avempace (Ibn Bājjah, Abū Bakr Muhammad Ibn Yahyā)
- Avendaño, Diego de
- Averroës (Ibn Rushd)
- Averroism, Latin
- Aversa, Raphael
- Avesta
- Aviat, Francesca Salesia, Bl.
- Avicebron (Ibn Gabirol, Solomon Ben Judah)
- Avicenna (Ibn Sīnā, Abū ‘Alīal-Ḥusayn)
- Avignon
- Avignon Papacy
- Ávila, Francisco de
- Avitus (Avy), St.
- Avitus of Vienne, St.
- Aviz, Order of
- Avranches, Council of
- Avril, Philippe
- Avvakum
- Axiology
- Axiomatic System
- Aymard, Bl.
- Aymer de la Chevalerie, Henriette
- Aymer de Lusignan
- Azevedo, Ignacio de, Bl.
- Azevedo, Luiz de
- Azor, Juan
- Aztec Religion
- Other back matter