David O. McKay showed John Birch Society president Welch's letter to Mark E. Petersen, who upon reading it said: "President McKay, Elder Harold B. Lee has some hair-raising stories to tell about the Birch Society which I am sure he will tell you, which I think would scare you to death. We have the Church, and if we live up to its teachings, we do not need to worry about what will happen to this country!"
[Source: David O. McKay diary as referenced in Gregory A. Prince and Wm. Robert Write, David O. McKay and the Rise of Modern Mormonism. Salt Lake City: University of Utah Press (2005)]