The Fourth Council of the Lateran meets, defining the doctrine of transubstantiation, the process by which bread and wine are, by that doctrine, said to transform into the body and blood of Christ.

The Fourth Council of the Lateran or Lateran IV was convoked by Pope Innocent III in April 1213 and opened at the Lateran Palace in Rome on 11 November 1215. Due to the great length of time between the council's convocation and its meeting, many bishops had the opportunity to attend this council, which is considered by the Catholic Church to be the twelfth ecumenical council.

Transubstantiation is, according to the teaching of the Catholic Church, "the change of the whole substance of bread into the substance of the Body of Christ and of the whole substance of wine into the substance of the Blood of Christ". This change is brought about in the eucharistic prayer through the efficacy of the word of Christ and by the action of the Holy Spirit. However, "the outward characteristics of bread and wine, that is the 'eucharistic species', remain unaltered". In this teaching, the notions of "substance" and "transubstantiation" are not linked with any particular theory of metaphysics.

Jesus, also referred to as Jesus Christ, Jesus of Nazareth, and many other names and titles, was a 1st-century Jewish preacher and religious leader. He is the central figure of Christianity, the world's largest religion. Most Christians consider Jesus to be the incarnation of God the Son and awaited messiah, or Christ, a descendant from the Davidic line that is prophesied in the Old Testament. Virtually all modern scholars of antiquity agree that Jesus existed historically. Accounts of Jesus's life are contained in the Gospels, especially the four canonical Gospels in the New Testament. Since the Enlightenment, academic research has yielded various views on the historical reliability of the Gospels and how closely they reflect the historical Jesus.