Hey Isabell :) Unfortunately I took this exam a long time ago, so I don't really remember what the exact question was. From my answers I can guess they asked how and why Christianity spread so fast throughout Europe. If I remember correctly they wanted to know what distinguished this religion from other religion. i.e. why Christianity was so succesful, Another subquestion was probably on how Christianity survived the collapse of the Roman Empire and how its role evolved since then. I hope this helps and good luck!