I want to test the ability of students to read a passage and answer questions about it. Could you please come up with a good question for the passage "In October 1529, Philip I, Landgrave of Hesse, convoked an assembly of German and Swiss theologians at the Marburg Colloquy, to establish doctrinal unity in the emerging Protestant states. Agreement was achieved on fourteen points out of fifteen, the exception being the nature of the Eucharist – the sacrament of the Lord's Supper—an issue crucial to Luther."? 

Unlike many modern day meetings which typically involve businessmen, who did this assembly bring together?