A few minutes before the ball came down on Times Square on New Year’s Eve, Paul Anka sang a song that has become a tradition for this event. It was “Imagine,” a 1971 song that John Lennon co-authored with his wife, Yoko Ono. The song has also become something of a controversy -- for the anti-religious point of view it expresses. “Imagine there’s no heaven,” says the first line of the song. “It…