
Henry Powell Spring in 1944; popularized by John F. Kennedy misquoting Dante (24 June 1963) http://www.bartleby.com/73/1211.html. Dante placed those who "non furon ribelli né fur fedeli" [were neither for nor against God] in a special region near the mouth of Hell; the lowest part of Hell, a lake of ice, was for traitors.
According to the John F. Kennedy Presidential Library & Museum http://www.jfklibrary.org/Research/Research-Aids/Ready-Reference/JFK-Quotations.aspx President Kennedy got his facts wrong. Dante never made this statement. The closest to what President Kennedy meant is in the Inferno where the souls in the ante-room of hell, who "lived without disgrace and without praise," and the coward angels, who did not rebel but did not resist the cohorts of Lucifer, are condemned to continually chase a banner that is forever changing course while being stung by wasps and horseflies.
See Canticle I (Inferno), Canto 3, vv 35-42 for the notion of neutrality and where JFK might have paraphrased from.
Misattributed