What is the theme in God Is Red: A Native View of Religion by Vine Deloria?

One of the most common themes in "God is Red: A Native View of Religion" by Vine Deloria, Jr. is greed. Ever since Columbus "discovered" America, it has been the practice of many settlers and pioneers to take land away from the Native Americans and to persecute, torture, and/or murder in order to profit from that which belonged to the Native Americans.