At times it needs a little more focus
A very well intentioned book with one main problem Krakauer can never decide where exactly to place the Lafferty Murders in the narrative therefore whatever issue about the nature of Mormonism is being discussed is always cut short and refocused to some kind of vague tie in that relates to these gruesome murders at least in the mind of the author.

So the narrative will be clipping along and you will be very interested in a particular aspect the Golden Plates, The Sons of Ham, plural marriage or the fact that in spite of the LDS's claim to the contrary there have always been competing factions within Mormonism and all of the sudden you will be back on the murders with no idea of how exactly the author bought you to that point. This is at times tragic because while it is a very well researched book at times its subject matter was so broad it felt like it was two or three books in one. This leads on my part to both feelings of confusion and a desire to hear more.

A
Asserting that America's "homegrown religion" is one steeped in and ultimately defined by persecution and violence, Krakauer's extensively researched book about Mormon fundamentalism is an informative look at an aspect of life that people are not always willing to see. Centering around a double murder in 1984, Krakauer deftly blends the beginnings of Mormonism, and the eventual splitting of the religion into Mainstream Mormonism and FLDS (the fundamentalist sect) with character portraits of those affected by the faith. The threads all merge into an outstanding picture that is not even close to boring - the entire narrative is endlessly interesting, and no one chapter brings down the whole. Each compliments the other and the flow is brilliant. Some may be bothered by the noticeable slant the author takes, but otherwise the tome that winningly combines the thriller with the non-fiction genres raises essential ethical and moral questions that every person should at least ponder - even if they themselves cannot answer them.

Spot on, Krakauer.
This is a story of extremism. Two Fundamentalist Mormons murder their sister-in-law and her two-year old child for her bad influence on their brother. Extreme, right? Yes. But the importance and genius of this book is how Krakauer connects extremism to its foundation - mainstream Mormonism. His reporting of the Mormon culture was spot on, in fact, so precise and accurate that many mainstream members resented the intrusion. He got it absolutely right and made the connection with extreme behavior undeniable. Well done, Krakauer.

Meticulously researched and well presented
There are far better and longer reviews than mine posted here, so I hesitated to even attempt one. However, I've traveled to many of the places described in Jon's book, including Separation Canyon (within the Grand Canyon) and Colorado City, long before the Fundamentalist LDS Church became one of the latest media targets.

Jon's book is very well researched, with first-person accounts, interviews, old letters and many other sources neatly pulled together. He had no intention of this book "bashing" the Mormon church, but the story he tells reveals much about the church, both good and bad.

Jon has a habit of telling stories that need to be told. Here he does his usual good job of doing just that- giving the 21st-century reader a clearer understanding about why Joseph Smith and his followers were hated, why America went to war against the Mormon church and why that same church today continues to be at odds with the rest of America and the world.

The book provided me with many "aha" moments- from the fate of John Wesley Powell's three men who left the expedition and who were "murdered" by Indians while in Mormon country to the reality of Elizabeth Smart's abduction and restoration.

fascinating story, which raises lots of questions

i've read a couple of krakauer's books (into thin air, into the wild), and have mostly loved them. i say "mostly", because, while i think he's a great writer and storyteller, and meticulous in his research, there's occasionally a hint of arrogance or smugness that i don't find appealing. that said, i found under the banner of heaven to be exceptionally fascinating.

if you're not familiar with krakauer's work, his books all have the same general approach: he tells a particular story, but places it within the context of its larger setting. in this case, the particular story is of a double murder, carried out by two fundamentalist mormon brothers (of their sister-in-law and her daughter) based on an alleged prophetic message from god. but the larger context is a thorough history of mainstream mormonism, and a much more detailed history and current-day description of the various fundamentalist mormon sects that have split off from the main lds faith.

of course, this book was published before the news-swirl earlier this year of the raid on a polygamous fundie compound in texas, and all the fall-out from that; but those characters play into this book (specifically, warren jeffs, the de facto leader of the particular splinter group that raided compound rolled up to). i learned a lot about mormonism, and even more about fundamentalist mormons (who, i have to add, krakauer treats with as much empathy and fairness as is possible).

all that said: what was really intriguing to me were the broader questions the book occasionally asks, but were regularly percolating in my mind, about religion. questions about civil disobedience, and how to respond when one's faith and government are at odds with each other. questions about hearing the voice of god. questions about authoritarian structures and communal discernment. even questions about marriage, fidelity, and intimacy. at one point, i jokingly said to my wife, "hey, maybe we should consider polygamy." she was at a particularly weary moment, and quickly responded, "could the other wife do all the cooking and cleaning?"

at the bottom line, under the banner of heaven bubbles up the danger of any one person saying he or she is speaking for god.