“One of President Kennedy’s favorite quotations was based upon an interpretation of Dante’s Inferno. As Robert Kennedy explained in 1964, ‘President Kennedy’s favorite quote was really from Dante, “The hottest places in Hell are reserved for those who in time of moral crisis preserve their neutrality.”‘ This supposed quotation is not actually in Dante’s work, but is based upon a similar one. In the Inferno, Dante and his guide Virgil, on their way to Hell, pass by a group of dead souls outside the entrance to Hell. These individuals, when alive, remained neutral at a time of great moral decision. Virgil explains to Dante that these souls cannot enter either Heaven or Hell because they did not choose one side or another. They are therefore worse than the greatest sinners in Hell because they are repugnant to both God and Satan alike, and have been left to mourn their fate as insignificant beings neither hailed nor cursed in life or death, endlessly travailing below Heaven but outside of Hell.”   –“John F. Kennedy’s Favorite Quotations: Dante’s Inferno,” from the JFK Library

For more, see Deborah Parker’s essay “The Historical Presidency: JFK’s Dante,” Presidential Studies Quarterly 48.2 (June 2018): 357-372.

The frequently misattributed quotation was also cited by Martin Luther King, Jr., in a 1967 address on the Vietnam War (see here).