Doubts about transubstantiation made him uneasy; some of Luther's tracts fell in his way, and he was comforted by Luther's dictum that salvation does not depend on human dogmata.
Soon after settling in Wolfenbiittel, Lessing found in the library the manuscript of a treatise by Berengarius of Tours on transubstantiation in reply to Lanfranc. This was the occasion of Lessing's powerful essay on Berengarius, in which he vindicated the latter's character as a serious and consistent thinker.
At Baden-in-Aargau in May and June 1526 a public disputation on the doctrine of transubstantiation was held, in which Eck and Thomas Murner were pitted against Johann Oecolampadius.
He is best known by his treatise on the Eucharist (De corpore et sanguine Domini liber), in which he controverted the doctrine of transubstantiation as taught in a similar work by his contemporary Radbertus Paschasius.
The seventy decrees of the council begin with a confession of faith directed against the Cathari and Waldenses, which is significant if only for the mention of a transubstantiation of the elements in the Lord's Supper.
The doctrine of transubstantiation was defined by the Lateran Council in 1215, and shortly afterwards the elevation and adoration of the Host were formally enjoined.
This reaffirmed the seven sacraments, transubstantiation and the invocation of saints, and declared the pope head of the Church, but adopted Luther's doctrine of justification by faith in a conditional way, as well as the marriage of priests, and considerably modified the theory and practice of the Mass.
In 1529 the famous conference between Luther and Zwingli on the subject of Transubstantiation took place there in the Rittersaal of the Schloss (see Marburg, Colloquy Of).
The rejection of the doctrine of transubstantiation at the Reformation naturally involved the suppression of the festival of Corpus Christi in the reformed Churches.
If so, parliament was told that temporal possessions ruin the church and drive out the Christian graces of faith, hope and charity; that the priesthood of the church in communion with Rome was not the priesthood Christ gave to his apostles; that the monk's vow of celibacy had for its consequence unnatural lust, and should not be imposed; that transubstantiation was a feigned miracle, and led people to idolatry; that prayers made over wine, bread, water, oil, salt, wax, incense, altars of stone, church walls, vestments, mitres, crosses, staves, were magical and should not be allowed; that kings should possess the jus episcopale, and bring good government into the church; that no special prayers should be made for the dead; that auricular confession made to the clergy, and declared to be necessary for salvation, was the root of clerical arrogance and the cause of indulgences and other abuses in pardoning sin; that all wars were against the principles of the New Testament, and were but murdering and plundering the poor to win glory for kings; that the vows of chastity laid upon nuns led to child murder; that many of the trades practised in the commonwealth, such as those of goldsmiths and armourers, were unnecessary and led to luxury and waste.