If I had to sum up this book using only one word, that word would be intense. The Sparrow is often included in lists of Very Important Sci-Fi Books, and now that I've read it, it's easy to see why. Author Mary Doria Russell incorporates many weighty themes into this book, which is both a classic first contact story and a meditation on the nature of religious faith. Although there are lighthearted moments, this is not what you would call a fun read. It's very dark (almost overwhelmingly so, although it never quite crosses that line), and should probably contain a trigger warning for victims of sexual violence. That being said, it's still one of the best books I've read in a long time, and I wholeheartedly recommend it to anyone who enjoys fiction that wrestles with difficult subjects. 
 There are plenty of other reviews that summarize the plot, so I'll skip right to the parts that I think make this book special. First, this is a sci-fi book that takes religion seriously. Father Sandoz's faith is at the core of this book, and his struggles and doubts are portrayed realistically. The non-religious characters respect the beliefs of their religious comrades, and vice versa. No one is judged for choosing to believe or not to believe, and the religious characters don't occupy the moral high ground by virtue of being religious. The characters' views all felt genuine, and Russell's prose about faith never felt cheap or contrived. I was surprised to see that some readers thought the idea of Jesuits in space was unrealistic. If/when we actually make first contact with alien life, I wouldn't be at all surprised to hear that Jesuits volunteered to be part of the mission. The rest of the story behind how the first contact team was formed didn't ring quite as true, but the idea of Jesuits expanding their mission field to outer space made total sense. Finally, this book features some of the most well-rounded characters I've ever read. This is not an easy book to read, but the payoff is well worth it!