Depends what era you mean right now we're sort of at peace with them but we used to be in a war against them so it all depends on time.
Medieval Christian Europe appeared with the decline of the Western Roman empire and the rise of Christianity. When Western Rome fell, cultural identity that once unified almost all of Europe disappeared. Christianity was able to fill this space by having people become more religious, identifying themselves with the Christian church. Moreover, Christianity gave political leaders legitimacy by Gods. Christianity became the center of the cultural life in western Europe and what is more important, it created a new social elite in which would dominate arts and sciences. Christianity gave an spiritual escape from the difficult Medieval ages. Europe was getting porer, there were outbreaks of many deadly illnesses and people were living in fear. Great soical differences additionaly made the life harder. Relgion gave hope to the poorest, that in the end, everyone was equal in front of the God. On the other hand, rich justified a lot of the actions as being neccessary and justified by the God's will. This resulted in even more fear and inequality. Medieval times are percieved as being one of the darkest in the Europes history, despite it's efforts to glorify the religion.
The answer is: The spending of public funds raised by borrowing rather than by taxation.
