Philip I of Hesse, after the Diet of Speyer had confirmed the edict of Worms, feels the need to reconcile the diverging views of Martin Luther and Huldruych Zwingli in order to develop a unified Protestant theology.

At the Marburg Colloquy, arranged in 1529 to establish doctrinal unity as a preliminary to the political unity of Protestantism, Johannes Oecolampadius defends Huldrych Zwingli's position on the nature of the Eucharist against that of Martin Luther.

It takes place between October 1 and October 4, 1529.

The leading Protestant reformers of the time attend at the behest of Philip.

His primary motivation for this conference is political; he wishes to unite the Protestant states in political alliance, and to this end, religious harmony as an important consideration.

Besides Luther and Zwingli, the reformers Stephan Agricola, Johannes Brenz, Martin Bucer, Caspar Hedio, Justus Jonas, Philipp Melanchthon, Johannes Oecolampadius, and Andreas Osiander participate in the meeting.

Luther’s failure to reach doctrinal accord with Zwingli, who denies Christ's real presence in any form in the Eucharist, splits the Reform movement.