What do Jesus and Karl Marx have in common? Well, to start with, they were both Jewish, and they both were Communists. That may startle you, but this shocking statement also depends on how you define "Jewish" and "Communist" - and reminds us that definitions are the key to understanding confusing episodes of both history and philosophy.
Jesus was spiritually, culturally, and genetically Jewish; Karl Marx merely happened to have Jewish grandparents; so they were both "Jewish", but in very different senses of the word. Jesus inspired his followers to put their money and material possessions into a common treasury, and share equally from it; this would qualify him as a "Communist" - but in a very different sense than Marx. Marx's version of Communism relied on the government as the ultimate power, on material objects as the ultimate reality, and on atheism as the ultimate belief. Jesus, to say the least, was not an atheist.
Many politicians are debating about "immigrants" now - but we must first define whether we are talking about legal or illegal immigrants.
Biologists are discussing "stem cells" these days - but are they examing those taken from adults, or from unborn babies?
It is precisely in these topics - the most emotional, passionate, and political themes - that we must focus most carefully on the definitions of words. Only then can we speak more rationally.
An atheist once attacked a philosopher with the often-repeated question, "can you really prove that God exists?" The philosopher, tired of the game, returned with a question, "can you even define the word 'God'?"