Melanchthon's temperament was conciliatory in a period that did not reward it, and after Luther's death in 1546 it made him the target of his own side.
The trouble began with the Leipzig Interim of 1548, an imperial settlement imposed after military defeat, under which he accepted the retention of certain Catholic practices, vestments, ceremonies and the like, on the ground that they were adiaphora, matters indifferent, and that keeping them was better than losing the preaching of the gospel entirely. A party which came to be called the Gnesio-Lutherans, the genuine Lutherans, held that in a time of persecution nothing is indifferent and that yielding on ceremony is yielding on confession. The argument was bitter and personal.
A second dispute followed over the will. Melanchthon's later formulations allowed the human will some role in conversion, alongside the word and the Spirit, and his opponents read that as a retreat from the position Luther had defended against Erasmus. A third concerned whether good works are necessary to salvation, on which his students split.
The Formula of Concord of 1577, drawn up seventeen years after his death to end the quarrels, settled most of them against his particular formulations while retaining the Augsburg Confession he had written as the foundation of the whole structure. The atlas records the disputes as a real theological division within a movement rather than as anyone's failure.