I don't know the whole story. I was not even born yet. But I read somewhere that Goldwater became less and less conservative as he aged?
Yea, some think that Goldwater's creeping liberalism was a result of a lack of religious faith. His funeral in 1998 was mostly devoid of religious symbols. Others think it was a product of his two liberal wives, the first of whom, Peggy of Muncie, IN, was on the Planned Parenthood board. Others thought it was a possibly homosexual relative. Others think it was mere western iconoclasm. He turned out also to be a big booster of Nelson Rockefeller for vice president and Ford for President in 1976.
"We're the new liberals of the Republican Party. Can you imagine that?" -Goldwater to Dole in 1996