Wittenberg Concord (1536), is a religious concordat signed by Reformed and Lutheran theologians and churchmen on May 29, 1536 as an attempted resolution of their differences with respect to the Real Presence of Christ's body and blood in the Eucharist. The Reformed who signed it were Martin Bucer, Wolfgang Fabricius Capito, Matthäus Alber, Martin Frecht, Jakob Otter, and Wolfgang Musculus. The Lutherans who signed were Martin Luther, Philipp Melanchthon, Johannes Bugenhagen, Justus Jonas, Caspar Cruciger, Justus Menius, Friedrich Myconius, Urban Rhegius, George Spalatin. This document defined the doctrine of the Real Presence of Christ's body and blood in the Eucharist as the Sacramental Union and maintained the real eating of the body and blood of Christ by "unworthy communicants" (manduc