Ecclesial communities contrasted in relation to Eucharistic theology:

Orthodox Christianity

• centered in the comprehensive mystical idea of metousiosis, a "great change of essence"
• the Eucharistic mystery bears an objective, Real Presence, par excellence.
• the Church's spiritual sacrifice of praise and the sacrifice of Christ in a mystical way are somehow one during this action of great offering and sacred love-feast.
• primary theological development from early Church Fathers, esp. the Eastern Fathers
• Eucharistic theology: The
  
  
  
  bread and wine truly are the Body and Blood of Christ, but the mechanics are not explored; stops short of the doctrine of Transubstantiation; interprets John 6 as well as 1 Corinthians 11 as applying to the Eucharist. Through the Holy Spirit's action, that which gives meaning to the bread and wine are changed by the mystery, and that which gives meaning to the partakers is changed by the mystery, and the partakers of the elements are commissioned by the mystery to live out the mystery in the world.
• the Divine Liturgy is never celebrated in private, as it is considered necessarily communal; there must be at least two or three people to receive Holy Communion.
• Generally closed communion, as determined by each bishop.
• Frequency: generally celebrated at least weekly and on "great feasts" and on Pascha, but in some places as little as four times per year. Members
  
  
  
  are encouraged to participate as often as it is offered, provided they are properly prepared through prayer, fasting, and recent confession.
• see Cappadocian Fathers, John Chrysostom, Ignatius of Antioch, Simeon Metaphrastes

Roman Catholic Church

• primary theological development derived from Thomism, 13th century
• Eucharistic theology: Transubstantiation is the means and mode of the Real Presence
• Various positions about Eucharistic Sacrifice which can appear contradictory: cf. Council of Trent
• "For not as common bread nor common drink do we receive these; but since Jesus Christ our Savior was made incarnate by the word of God .. the food which has been made into the Eucharist by the Eucharistic prayer set down by Him, and by the change of which our blood and flesh is nourished, is both the flesh and the blood of that incarnated Jesus." St. Justin Martyr ()
• Closed communion.
• Frequency: priests celebrate the Mass daily, with members encouraged to participate at least once per week if they are properly prepared (ie. not having committed a mortal sin since last confession and observing the Eucharistic fast). Catholics are only required to receive communion once per year.
• Private masses: a priest may celebrate private masses, with no one but himself to receive communion. The Church recommends that priests say Mass daily, but they are not so required. In fact, they may not celebrate (except for grave reason) if they themselves are in a state of mortal sin.
• see Thomas Aquinas

Lutherans (and Moravians)

• Primary theological development from Martin Luther and Philipp Melanchthon, 16th century
• Eucharistic theology: Real Presence
• Leuenberg Agreement (1973) with the Reformed and United Churches (Lutheran and Reformed) of Germany: