In Christian theology communicatio idiomatum ("sharing of attributes") is a term from the theology of the Incarnation, attempting to explain the relationship between two natures (divine and human) in one person (Jesus Christ). The theory is that both the properties of God the Son and the properties of the human nature can be ascribed to the person Jesus- a "Communication of Idioms" or attributes. The assumption behind the theory, based on Scripture and the Church Fathers, is that God the Father and the Holy Spirit have the same rights and interest in all things created except in the human nature of Jesus Christ. His person is a result of the personal union between God the Son and (a) human nature; in other words the person of Jesus Christ has divine attributes and the divine being of God the Son is the subject of human properties. It is this theory which makes it possible for Christians to say "Christ is God" or "God is man" — two otherwise mutually exclusive concepts have been united through the communication of the properties of the two natures to the one person Jesus Christ. The guidelines for incarnational orthodoxy were set forth most authoritatively at the Council of Chalcedon (AD 451). Its definition affirmed that Jesus Christ's two natures - divine and human - could not be confused or mixed on one hand, separated or divided on the other. The doctrine has since the Protestant Reformation served as a bone of contention between Lutheran and Reformed Christians. Lutherans hold to the view that Jesus Christ's human nature takes on the predicates of the divine nature. This imputation allows not only for God's glory to be contained and manifest in the human person at the resurrection, but in this age it also provides the ground for the human presence of Jesus Christ "in, within, under" the bread and wine of the eucharist (the sacramental union view of the Lord's Supper). In Reformed doctrine, the communicatio idiomatum, while effective for the purpose of salvation, does not refer to a sharing of divine attributes. Jesus Christ, the bodily man, remains in heaven as high priest, even while in his divine nature he is omnipresent. This coincides with the Calvinistic view of the Lord's Supper (real presence), the belief that Christ is truly present at the meal, though not substantially and particularly joined to the elements. Both Lutherans and Reformed claim to uphold the Christological definition offered at the Council of Chalcedon. To wit, where Lutherans can make bolder claims regarding the unity of the person of Christ, the Reformed can make bolder claims for the preservation of the human nature of Christ. In more heated rhetoric, Lutheranism is accused of promoting monophysitism, and the Reformed a certain Nestorianism.