Holy travellers returned home with relics but also with Roman practices, which allowed Gregory to become the arbiter and leader of Christianity across Europe. When Gregory died in 604 he was buried in St Peter's, where his epitaph read, "God's consul". He'd enriched and empowered the papacy, combining the old with the new. He was truly the high priest of city and church. The Pope now headed the most influential organisation in Western Europe. And Rome was its power base. The modern papacy, as we know it, was taking shape. But Rome now faced a completely new threat. A new religious revelation was on the march. Islam. In a few decades, the Arabs had conquered a vast empire. They captured Jerusalem, leaving Rome the one and only Holy City of Christendom. Rome feared it would be next. The city needed an ally. Charlemagne, King of the Franks, was a gifted soldier-statesman who had conquered much of Western and Central Europe.


朝圣者带着文物回到家乡，同时也带回了罗马的习俗；格里高利因此得以成为整个欧洲基督教界的权威和领袖。公元604年格里高利去世时，被安葬在圣彼得大教堂。他的墓志铭上写着“神的领事”。他整合新旧（权利体系），从而丰富并巩固了教皇的职权。他真正是城市和教会的大祭司（注：可能是指行政、宗教）。这位教皇现在统领着西欧最有影响力的组织。而罗马是该组织的权力基础。今天我们所熟知的教皇一职正在逐渐成形。但是，罗马现在面临着一个全新的威胁。一个新的宗教正行进在征途上。这就是伊斯兰教。在几十年期间里，阿拉伯人攻下了一个庞大的帝国。他们占领了耶路撒冷，使罗马成为唯一一个基督教的神圣之城。罗马城担心自己将是下一个（被拿下的城市）。这座城市需要一个盟友。法兰克国王查理曼，是一个天才的军人政治家。他征服了西欧和中欧的大部分地区。