Rewriting history

I am tempted to say that Pope Francis' repudiation of the doctrine of discovery is a rewriting of ALL of history; let's just say he has opened the door to a tremendous rewriting of history, ESPECIALLY world history. The repudiation is a data point of great importance, whatever you think of its substance, which will have to be taken into account in any large-scale history. Some people I know and respect will scoff and probably say something about revisionist history. To which I have to respond, What do historians do if not revise our understanding of history?