Interesting. Where do you get your quote? JFK went on record in 1960 to happily accept the Liberal Party of New York's nomination and gave a speech to them saying he was "proud" to be a liberal and believed in "progressive" big-government policies on education, health care, and welfare.
Either your quote from 1953 is inaccurate, JFK had "evolved" in seven years, or JFK was simply two faced and told different audiences what they wanted to hear.