I don’t know if speculative anthropology is a genre, but if it were, The Sparrow would be an exemplary piece. It gets categorized as science fiction, but the science is the least of its concerns. Yes, there are spaceships and aliens. But the spaceships are dealt with just enough to assure us that the trip is possible. It’s far, but not too far. It makes the plot timelines work, but doesn’t get into details of, say, rocket propulsion. Upon arrival at an alien planet, our explorers are lucky to be perfectly adapted to the plant, in mass, in atmosphere, and even in food sources.
The main concern of the story is the encounter with an alien society and how that might conflict with our ideas of meaning and faith. Our crew discovers an advanced society who evolved customs and norms under a vastly different ecosystem. The alien’s actions and attitudes towards each other are troubling. Actions that seem cartoonishly evil to us are the accepted tradeoff for a smoothly running society. If you believe–as the main character does–that God is leading you to this place, only to find yourself on the losing side of in this sometimes brutal society, you’re going to have second thoughts about the possibility of a loving God and his (or her) involvement in the world.
This book is not here to answer your questions, it is here to raise questions didn’t think to ask. Don’t look for an affirmation of your own sense of justice, or vengeance. At the end, our main character is having a crisis of faith, and the book tries to put us in that same frame of mind.