One way to think about transubstantiation is "trans" means transformed and "substan-" means substance. So, at the taking of communion the very substance of bread and wine is miraculously changed into the real Body and Blood of Christ, while only the accidents (appearances) remain. This is the view of the Roman Catholic church.

This understanding was first formalised at the Fourth Lateran Council (1215) and defined by the Council of Trent (1545-63) based on a literal interpretation of Christ’s words "This is my body… This is my blood." It frames the Lord’s Supper as a true sacramental sacrifice and real participation in Christ’s body. Communion is not symbol, but a mystery of faith: the one incarnate Christ is really present under the signs of bread and wine. The term "transubstantiation" comes from St Thomas Aquinas (†1274), who explained that God effects a complete change of substance (Latin substantia).

Scriptural Support

• At the Last Supper, Jesus declared the bread to be his actual Body and the wine his actual Blood (Mt 26:26-28; Mk 14:22-24; Lk 22:19-20). There is no indication of it being symbolic and at face value transubstantiation makes sense.
• Paul warns that those who "eat and drink" the Lord’s Supper unworthily "eat and drink judgement to themselves" (1 Cor 11:27-29). Transubstantiationalists interpret this as referring to the true Body and Blood under the species of bread and wine.
• In John 6, Jesus insists "Unless you eat the flesh of the Son of Man and drink his blood, you have no life in you" (Jn 6:53), and adds "Whoever feeds on my flesh and drinks my blood abides in me" (6:56). Catholics take this literally as well, arguing that Christ requires actual (though sacramental) reception of his flesh and blood.
• Other passages cited include Jesus’ statement in John 14:18-20 ("I will not leave you as orphans… you will see me") and the communal language of 1 Corinthians 10:16-17 ("The bread which we break, is it not the communion of the body of Christ?").

In summary, transubstantiation treats the institution narratives and Eucharistic language in the New Testament as indicating a real, physical presence of Christ in the elements, not mere symbolism or memory.

Historical Witness

• Augustine wrote of the Mass as containing Christ’s very body, observing "not all bread, but that which receives the blessing of Christ, becomes Christ’s Body" (Sermons 227, On the Day of the Lord’s Supper.).
• St John Chrysostom similarly insisted, "‘This is my body,’ he says - this word transforms the things offered into the Body of Christ" (Sermons 227, On the Day of the Lord’s Supper).
• St Cyril of Jerusalem (4th c.) taught that after the invocation, "the bread becomes the Body of Christ and the wine the Blood of Christ" (Catechetical Lectures, Lecture 22 (Mystagogic Catecheses), no. 2 & 9).
• Other Fathers like Athanasius (Letter to Serapion, 1.20), Justin Martyr (First Apology, chapter 66) and Gregory Nazianzen (Oration 45 (On Holy Pascha), 9) testify that the bread and wine cease to be common and truly become Christ’s flesh and blood.

In medieval Catholicism, theologians like Paschasius Radbertus and later St Thomas Aquinas developed the explanation: using the Aristotelian ideas of "substance" and "accidents," Aquinas defines transubstantiation as the miraculous change of all substance of bread into Christ’s body, and of wine into his blood.

• Aristotelian "substance"
  • The substance of a thing is its essential reality-what it truly is.
  • It is the underlying essence that makes a thing what it is.
  • For example, the substance of bread is "breadness"-its true, essential identity.
• Aristotelian "Accidents"
  • Accidents are the non-essential properties that can change without altering the substance.
  • These include appearance, taste, texture, colour, smell, and quantity.
  • For example, bread can be toasted (change in appearance and texture), but it remains bread-its substance does not change.

The Council of Trent (1551) reaffirmed this: "after the consecration…the Lord Jesus Christ… is truly, really and substantially contained in the august sacrament of the Holy Eucharist under the appearance of those sensible things".  Trent even anathematised (Canon 1) any view denying that Christ is "truly, really and substantially" present and insisting he is only in the Supper as a sign or figure.

The Problem with Transubstantiation

Reliance on Aristotelian Metaphysics

First, it relies on Aristotelian metaphysics (substance/accidents) not found in Scripture. Reformers like Luther and Calvin insisted that Christ’s words can stand on their own without a scholastic explanation. Luther, warned that philosophy cannot fully grasp the mystery. We must "take reason captive to the obedience of Christ" and believe by faith that "the body of Christ is in the bread… and the bread is the body of Christ" (The Babylonian Captivity of the Church, 1520; Confession Concerning Christ’s Supper, 1528). He rejected the need for transubstantiation’s explanation of accidents, arguing that Christ’s real body and blood are truly present by God’s power even if bread remains bread.  Calvin likewise scorned the notion of a "substance" change effected by human words as a "fictitious" invention of men (even calling it "the work of Satan" in his Institutes).

• Luther, Against the Heavenly Prophets, 1525 - "It is not necessary that the bread and wine cease to be present… God is able to include His body also in the bread."

Contradiction of Physical Presence & Christ's Ascension

A second major problem has to do with the ontological and spatial implications of the physical transformation of the bread & wine. The problem with this is that Christ ascended bodily into heaven (Acts 1:9-11), where He remains at God's right hand (Rom. 8:34; cf. Col. 3:1; Heb. 1:3). The Chalcedonian Creed affirms that Christ’s two natures (divine and human) are united without confusion, change, division, or separation. His human nature remains truly human-finite, local, and spatially located, though glorified. Therefore, His human body is not omnipresent. Only the divine nature of Christ participates in ubiquity, being omnipresent.

Transubstantiation implies that Christ’s glorified human body can be substantially present in countless Eucharistic celebrations simultaneously across the globe. This is a Christological dilemma. If the divine attribute of omnipresence is communicated to Christ’s human nature, then His divine and human natures are being mixed together in a way that the Bible and the early Church councils clearly rejected.

Violating the Finality of Christ's Sacrifice

According to Catholic teaching, the Mass (including the Eucharist) is a re-presentation of the one sacrifice of Calvary in an unbloody manner. While nuanced, this still raises biblical concerns. Hebrews underscores that Christ’s offering is once for all (ἐφάπαξ, ephapax), not to be repeated or re-enacted (Hebrews 10:10, 12; 7:27). Hebrew's language is temporal and eschatological: Christ’s work was definitive and decisive, which is in contrast to the repetition of the Levitical system. The image of Christ sitting down at the right hand of God symbolises completion-a cessation of sacrificial activity. Maintaining that the Eucharistic offering is sacrificial in nature (even if distinct in mode) obscures the finality of Calvary.

The idea that the Eucharist "makes present" the sacrifice in a real and substantial way suggests an ongoing priestly action that stands in tension with Hebrews’ portrayal of Christ’s singular and sufficient offering. While Rome argues that the Eucharist is a memorial in the sense of anamnesis (making the past event real and efficacious in the present) this understanding conflates sacramental participation with sacrificial re-enactment. Even if formally denied, Mass is functionally equivalent to a repeated sacrifice.

Other Communion Views: Consubstantiation or Sacramental Union | Spiritual Presence | Memorialist Communion

Sources

• Aquinas, T. (1274/1947). Summa Theologica (Fathers of the English Dominican Province, Trans.). Benziger Bros. (Original work published 1274)
• Augustine. (n.d.). Sermon 227: On the Day of the Lord’s Supper. In P. Schaff (Ed.), Nicene and Post-Nicene Fathers: First Series (Vol. 6). Christian Literature Publishing Co.
• Calvin, J. (1536/2008). Institutes of the Christian Religion (H. Beveridge, Trans.). Hendrickson Publishers. (Original work published 1536)
• Catechism of the Catholic Church. (1994). St Pauls Publications.
• Council of Trent. (1545-1563/1978). The Canons and Decrees of the Council of Trent (H. J. Schroeder, Trans.). TAN Books.
• Fourth Lateran Council. (1215). Constitutiones Concilii Quarti Lateranensis. In H. Denzinger (Ed.), The Sources of Catholic Dogma (R. Deferrari, Trans.). Loreto Publications.
• Gregory Nazianzen. (n.d.). Oration 45 (On Holy Pascha). In P. Schaff & H. Wace (Eds.), Nicene and Post-Nicene Fathers: Second Series (Vol. 7). Christian Literature Publishing Co.
• John Chrysostom. (n.d.). Homilies on Matthew. In P. Schaff (Ed.), Nicene and Post-Nicene Fathers: First Series (Vol. 10). Christian Literature Publishing Co.
• Justin Martyr. (2nd century/2006). The First Apology. In M. Dods & A. Roberts (Trans.), The Apostolic Fathers with Justin Martyr and Irenaeus. Hendrickson Publishers.
• Luther, M. (1520/1957). The Babylonian Captivity of the Church. In T. G. Tappert (Ed.), Luther’s Works (Vol. 36, pp. 3-126). Fortress Press.
• Luther, M. (1525/1958). Against the Heavenly Prophets. In T. G. Tappert (Ed.), Luther’s Works (Vol. 40, pp. 79-223). Fortress Press.
• Luther, M. (1528/1959). Confession Concerning Christ’s Supper. In T. G. Tappert (Ed.), Luther’s Works (Vol. 37, pp. 151-372). Fortress Press.
• Paschasius Radbertus. (9th century/1990). On the Body and Blood of the Lord (J. M. Rosenthal, Trans.). Catholic University of America Press.
• St. Cyril of Jerusalem. (4th century/2005). Catechetical Lectures (E. W. Gifford, Trans.). St Vladimir’s Seminary Press.