Showing 246 terms beginning with O.
- Oak, sacred
- Oates, Titus
- Oath
- Obadiah
- Obbenites
- Obedience
- Ober-Ammergau
- Oberlin, Jean F.
- Oberlin College
- Obi superstition
- Oblate di Tor de' Specchi
- Oblates
- Oblations
- Obligation
- Obodas II.
- Obookaiah, Henry
- Oboth
- Obotrite Wends
- O'Bryan, William
- Observantine Franciscans
- Observantists
- Occam, William of
- Occasional address
- Occasionalism
- Occom, Samson
- Occult phenomena
- Occultism
- Occultus
- Occum, Samson
- Oceania, missions in
- Ochino, Bernardino
- Ockham. See
- O'Connor, Jan A.
- Octave
- Octavian. See
- Oda of Canterbury
- Odd Order Brethren
- Oddo Colonna
- Odenatus
- Odes of Solomon
- Odescalchi, Benedetto
- Odilo of Cluny
- Odin
- Odland, Sigurd V.
- Odo (of Canterbury)
- Odoric of Pordenone
- Œcolampadius, Johannes
- Œconomus, Constantinus
- Œcumenical councils
- Œcumenius
- Oeder, Georg L.
- Oedmann, Samuel
- Oehler, Gustav F. von
- Oesterley, William O. E.
- Oetinger, Friedrich C.
- Oettli, Samuel
- Offa
- Offering, burnt
- Offerings. See also
- Offertory
- Offices of Christ
- Official
- Og
- Ogdoads
- O'Gorman, Thomas
- O'Hara, Henry S.
- Ohio, Joint Synod of Lutheran
- Oil
- O'Kelly, James
- Olaf Haraldson
- Old Catholic Church of Holland
- Oldcastle, Sir John
- Oldenbarneveldt
- Oldenburg
- Oldratus, Johannes
- Olearius, Adam
- Olevianus (Olevian), Kaspar
- Olga, Saint
- Olier, Jean J.
- Olimpia, Donna
- Olin, Stephen
- Olive oil
- Olivers, Thomas
- Olives, Mount of
- Olivet
- Olivetan, Pierre R.
- Olivetus, Lupus
- Olivi, Pierre J.
- Olivier, Pierre R.
- Olivieri, D. F.
- Olivists
- Olmsted, Charles S.
- Olney hymns
- Olsen, Isaac
- Olshausen, Hermann
- Olsson, Olaf
- Oltramare, Marc J. H.
- Olympius of Ravenna
- Omaha Theological Seminary
- Omar (caliph)
- O'Meara, Thomas R.
- Omer
- Ometecutli
- Omniscience and freedom
- Omophorion
- Omri
- On
- Oncken, Johann G.
- Onderdonk, Henry U.
- Ondereick, Theodor
- Oneida community
- O'Neill, S. W.
- Onias III. (IV.)
- Onions
- Onkelos
- Ono
- Ontological argument
- Onyx
- Oort, Henricus
- Oosterzee, Jan J. van
- Opfer, Joachim
- Opheilē, opheilēma
- Ophians
- Ophir
- Ophites
- Ophra (Ophrah)
- Oppert, Jules
- Optatus
- Optimism
- Option
- Opus Operantis
- Opus Operatum
- Opzoomer, Cornelis W.
- Oracles
- Oral law, Hebrew
- Orange Free State, Dutch Reformed Church in
- Orange Free State, River Colony
- Orarium
- Oratorians
- Oratorio
- Oratorium divini amoris
- Oratory
- Orbelian, Stephen
- Orchards
- Ordeal
- Order of Christ
- Ordericus Vitalis
- Orders, Anglican
- Ordiex, S. P.
- Ordinal
- Ordinances
- Ordinary
- Ordination
- Ording, Johannes
- Ordo fontis Ebraldi
- Ordre du Saint Esprit
- Oreglia di Santo Stefano L.
- Orelli, Hans C. von
- Organ
- Organization, ecclesiastical
- Oriental monasticism
- Orientius
- Origen
- Origenistic Controversies
- Origin of Christian baptism
- Original Antiburghers
- Orion
- Orléans, Synods of
- Orme, William
- Ormuzd
- Ornaments
- Ornithopolis
- Orontes
- Orosius, Paulus
- Orpah
- Orpen, R. D'Audemer
- Orphanages
- Orpheus
- Orr, James
- Orsini, G. G.
- Orsini-Gravina, Pietro F.
- Orthodox Catholic Church
- Orthodoxy
- Orthography, Hebrew
- Ortlibians
- Ortlieb of Strasburg
- Orton, Job
- Osborne, Edward W.
- Osgood, Howard
- Oshaya, rabbi
- Osiander, Andreas
- Osiandrian Controversy
- Osiris
- Osmer, saint
- Osmund (Osmond), Saint
- Osnabrueck, Bishopric of
- Ossat, Arnaud d'
- Ossuarium
- Osterwald, Jean F.
- Ostiarius
- Ostorodt, Christoph
- Ostrogoths
- Osuna, Francisco de
- Oswald, Saint
- Oswin
- Oswy
- Otfrid of Weissenburg
- Othman
- Othniel
- Otho. See
- Otho, Anton
- Otmar, abbot
- O'Toole, Laurence, Saint
- Otte, Christoph H.
- Otter, Jakob
- Otterbein, Philip W.
- Ottley, Edward B.
- Otto II., duke
- Otto I., emperor
- Otto IV., emperor
- Otto of Bamberg
- Otto, Johann K. T. von
- Ottoboni, Pietro
- Ottocar of Bohemia
- Ottow, C. W.
- Ouateblé, François
- Oudin, Remi-Casimir
- Ouen, Saint
- Our Lady of Loreto
- Ousia
- Outdoor relief
- Oven
- Ovenden, Charles T.
- Overbeck, Friedrich
- Overberg, Bernhard H.
- Overton, John H.
- Owen, John
- Ownership, private
- Owtred, John
- Ox
- Oxenden, Ashton
- Oxenham, Henry N.
- Oxenstierna, Axel
- Oxford
- Oxyrhyncus logia
- Ozanam, Antoine F.