What is the author's style in Custer Died for Your Sins: An Indian Manifesto by Vine Deloria?

Deloria's style is somewhat academic. We get a sense throughout the book that in terms of both his reasons for writing and his intended audience, he is speaking with one purpose (education), but with the intent of reaching two different factions - whites and blacks. While he clearly intends to broaden the perspectives of both, those intentions manifest in different ways. His apparent intention towards whites is to divert them from fear-driven action towards understanding-driven consideration. Towards Indians, his intention is to divert them from resentment-driven reaction to compassion-driven action.