Lennon was an atheist, and I guess he was trying to draw to peoples attention the plastic 'Peace on Earth' Christmas message with the reality of rampant consumerism, and relentless death through war and indiscriminate killing. Hence he conveys this hypocrisy with a mournful song. Then again he might have been just off his tits as he also wrote ''you are the egg man, we are the egg men, I am the walrus, coo coo cachoo''