Reformed Christianity is a branch of Protestantism. In the context of the sixteenth century Reformation the "reformed" tradition typically describes those churches that identified with the theological work of John Calvin, although in reality the reformed tradition is much more theologically pluralistic and has been influenced by other theologians and thinkers such as Huldrych Zwingli, Martin Bucer and others. Within the nebula of early dissenting Christianities emerging in the sixteenth century reformation on the continent and in Britain one can group them into somewhat reductive camps - Anglicanism, Lutheranism and Calvinism - although even these groupings are problematic and need to be further interrogated.

Calvin, as you may recall, was a French theologian who established himself in the city of Geneva in the 1540s, and advocated for a form of the Christian religion that emphasized the absolute sovereignty of God over all Creation, the totally depravity of all human beings, and predestination. According to Calvin, since the beginning of time God possessed foreknowledge of the soteriological fate (whether a person would be saved or not) of all human beings. A person therefore could never effect their own salvation through their own works, they either were destined to be saved or destined to be damned. As you might imagine, this belief caused no small amount of anxiety amongst Christian believers, however many came to believe that those who faithfully preached the Gospel and believed in the Christian faith would be saved, and that their good works were indicative of the legitimacy of their faith - the distinction once again being that works flow from faith as a healthy tree produces good fruit, rather than works earning salvation.

However as stated above the reformed tradition is not reducible to Calvin. The Swiss reformer Huldrych Zwingli famously disagreed with John Calvin on a number of important Christian doctrines, in particular the nature of the Eucharist. According to Roman Catholics, at the time of the consecration the elements of the bread and wine are transubstantiated or changed into the real body and blood of Christ. John Calvin however disagreed with this principle and suggested that Christ was present in the elements in a comparatively abstract and spiritual manner. Zwingli dissented from both of these stances, and contended that the institution of the eucharist at the Last Supper was actually much more commemorative. He believed that when believers participated in this ritual they merely remembered the sacrifice of Christ and reflected prayerfully on his words at the Last Supper before his death. This was in some sense re-enactment and did not include the spiritual transformation of the elements. Zwingli's ideas have been termed Memorialism and are common to some Baptist churches and communities, however some have objected to this understanding of Zwingli and believe him to be misunderstood. According to this view he was not saying that Christ is not present at all during this ritual but rather that he is not localized in the elements being consumed. Christ as Logos is perhaps present in the hearts of believers but not in the elements.