Answer: Great plague took place in the 14th-century western and southern Europe. There were two big consequences. 1) significant reduction of the population, 2) it was interpreted as a divine punishment for the immorality spreading within the church (and papacy) which led to phenomenon of first criticists of the church and social reformers of the church and first reform movements. Point one and two points to - crisis of authority of the church/papacy as an institution of the medieval society.
Explanation: considerable part of Europe lost at least 40% of the population, church suffered crisis of authority, there were conflicts between papacy and emperors/kings (Louis the Bavarian), new phonomenon of two or three papacies emerged, there were attempts to solve these problems by means of councils (1415 Konstanz in Germany, 1419 Pisa in Italy).
