What is the point of establishing missions?
Missions are good for many reasons. First, they will provide an even flow of indian converts to your colonies. Converts are good for outdoor work such as fishing, farming, planting, lumber cutting, ore/silver mining, and fur trapping. Second, missions will dramatically reduce the alarm created in that indian village. Third, your missionaries will slowly but surely convince the natives that the other European Powers are no good, assuring a more hostile attitude towards your rivals. And finally, every mission you have within a tribe contributes to lowering the amount of gold that tribe will demand when you ask them to join forces against one of your rivals.