Exodus 23:20-33

God tells the Israelites that He will send an angel ahead of them as they go take possession of the Promised Land and do battle with enemy nations.

What does this have to do with Christians today? Are they also called to take authority over other nations? Isn't this the kind of stuff that led to the detestable crusades a few centuries ago?

Or is there another way Jesus calls us go into enemy territory and use the authority He has given us?