In Christianity, a Eucharistic miracle is any miracle involving the Eucharist. The Roman Catholic, Lutheran, Eastern Orthodox, Methodist, Anglican and Oriental Orthodox Churches believe that Christ is really made manifest in the Eucharist and deem this a Eucharistic miracle; however, this is to be distinguished from other manifestations of God. The Catholic Church distinguishes between divine revelation, such as the Eucharist, and private revelation, such as Eucharistic miracles. In general, reported Eucharistic miracles usually consist of unexplainable phenomena such as consecrated Hosts visibly transforming into myocardium tissue, being preserved for extremely long stretches of time, surviving being thrown into fire, bleeding, or even sustaining people for decades.
Verification of Eucharistic miracles often depends on the religious branch reporting the supposed miracle, but in the case of the Catholic Church, a special task-force or commission investigates supposed Eucharistic miracles before deciding whether they are "worthy of belief." As with other private revelations, such as Marian apparitions, belief in approved miracles is not mandated by the Catholic Church, but often serves to reassure believers of God's presence or as the means to "send a message" to the population at large. Anglican Churches have also reported extraordinary Eucharistic miracles.
Real Presence of Christ in the Eucharist
Roman Catholic Eucharistic Doctrine draws upon a quasi-Aristotelian understanding of reality, in which the core substance or essential reality of a given thing is bound to, but not equivalent with, its sensible realities or accidents. In the celebration of the Eucharist, by means of the consecratory Eucharistic Prayer, the actual substance of the bread and wine are changed into the body and blood of Christ. This change in substance is not, however, the outward appearances of the bread and wine—their accidents—which remain as before. This substantial change is called transubstantiation, a term reserved to describe the change itself.