Craig Foster considers Krakauer's book both anti-religion and anti-Mormon.
Craig Foster, "Doing Violence to Journalistic Integrity," FARMS Review of Books 16, no. 1 (2004): 174
In conclusion, Krakauer's Under the Banner of Heaven has not lived up to expectations nor to its pre- and postpublication publicity. Moreover, his obvious biases against both religion in general and the Church of Jesus Christ in particular have made the book nothing more than a flawed sensationalistic work that, it is hoped, will soon be forgotten along with many similar anti-Mormon works of the past.