[David O. McKay] N. Eldon Tanner inquired in May 1969 "if a man were an avowed communist, would our position be to excommunicate him or disqualify him for any position in the Church," McKay responded that he should not hold any church position, but allowed that he might remain a member of the church."
[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)]