Authority
Doctrine
Catholic
Scripture, Tradition, and the Magisterium together.
Eastern Orthodox
Scripture and Holy Tradition; conciliar consensus.
Protestant
Sola scriptura in most traditions; confessions inform interpretation.
The Doctrine Explorer
How the traditions teach
A concise museum plaque for each topic — Catholic, Eastern Orthodox, and Protestant confession, side by side, in their own key.
Scripture
Doctrine
Catholic
73 books including Deuterocanon; Vulgate tradition.
Eastern Orthodox
Old Testament follows the Septuagint; broader canon.
Protestant
66 books; Apocrypha rejected (Reformed) or read for edification (Anglican/Lutheran).
Tradition
Doctrine
Catholic
Sacred Tradition, equal in dignity to Scripture.
Eastern Orthodox
Holy Tradition as the life of the Spirit in the Church; Scripture is part of it.
Protestant
Tradition normed by Scripture; sometimes minimally received.
Baptism
Doctrine
Catholic
Regenerative; usually by infusion in infancy.
Eastern Orthodox
Regenerative; triple immersion, with chrismation and Eucharist.
Protestant
Ranges from infant covenantal/regenerative to believer's baptism by immersion.
Eucharist
Doctrine
Catholic
Transubstantiation; real presence under the species.
Eastern Orthodox
True Body and Blood; mystery without scholastic definition.
Protestant
Real presence (Lutheran), spiritual presence (Reformed), memorial (Baptist/Zwinglian).
Salvation
Doctrine
Catholic
Grace, faith working through love; sacramental life.
Eastern Orthodox
Theosis through participation in divine life.
Protestant
Justification by grace through faith; sanctification follows.
Mary
Doctrine
Catholic
Theotokos; Immaculate Conception (1854); Assumption (1950).
Eastern Orthodox
Theotokos; ever-virgin; honored above all saints; rejects Immaculate Conception as defined.
Protestant
Honored as mother of the Lord; devotional cult generally rejected.
Saints
Doctrine
Catholic
Veneration and intercession; formal canonization.
Eastern Orthodox
Veneration and intercession; glorification by the Church.
Protestant
Honored as examples; intercession typically not practiced.
Church Structure
Doctrine
Catholic
Episcopal, with universal jurisdiction of the pope.
Eastern Orthodox
Episcopal, conciliar; primacy of honor for Constantinople.
Protestant
Episcopal, presbyterian, or congregational depending on tradition.
Apostolic Succession
Doctrine
Catholic
Bishops in unbroken succession from the apostles.
Eastern Orthodox
Bishops in unbroken succession; tied to right faith and communion.
Protestant
Varies; many traditions affirm a succession of doctrine rather than office.
Eschatology
Doctrine
Catholic
Particular judgment, purgatory, general resurrection, final judgment.
Eastern Orthodox
Toll-houses (debated), prayer for the dead, general resurrection, final judgment.
Protestant
Heaven and hell at death; final resurrection and judgment; purgatory rejected.
Filioque
Doctrine
Catholic
The Spirit proceeds from the Father and the Son (Filioque) as from one principle.
Eastern Orthodox
The Spirit proceeds from the Father alone; the Filioque addition is rejected as an unauthorized change to the Creed.
Protestant
Almost universally retains the Western Filioque in the Nicene Creed.
Icons & Images
Doctrine
Catholic
Sacred images and statues honored; veneration distinguished from worship.
Eastern Orthodox
Icons as windows on heaven; veneration defined at Nicaea II (787); no three-dimensional statuary.
Protestant
Reformed traditions removed images; Lutheran and Anglican traditions retained many but rejected the veneration cult.
Original Sin
Doctrine
Catholic
A deprivation of original holiness transmitted to all Adam's descendants — contracted, not personally committed (CCC 404–405). It brings concupiscence and the loss of grace, and is remitted by baptism; the Augustinian language of 'guilt' refers to this fallen state, not to personal culpability for Adam's act.
Eastern Orthodox
Inherited mortality and the wound of sin, not inherited guilt; the fall is a shared condition healed in Christ.
Protestant
Total depravity or radical corruption; humans are unable to save themselves apart from grace.
Marriage & Divorce
Doctrine
Catholic
Sacramental and indissoluble; annulment recognizes that a valid marriage never existed.
Eastern Orthodox
A mystery of the Church; remarriage after divorce is permitted under strict pastoral economia.
Protestant
A covenant blessed by the Church; divorce and remarriage generally permitted on grounds set by each tradition.
Christology
Doctrine
Catholic
Chalcedonian: one Person in two natures, divine and human, without confusion, change, division, or separation.
Eastern Orthodox
Chalcedonian in a Cyrillian key; two natures fully united in the one hypostasis of the Word.
Protestant
Universally Chalcedonian; Reformed traditions add the extra Calvinisticum on the Word's continued cosmic reign.