The Anti-Idiotarian Rottweiler had a few things to say about socialism, and why it doesn't work. In his comments thread, however, one of his commenters summed it up, using the best analogy I have ever heard:
I believe this is what happens when you disregard Christ's admonition to give onto Ceasar what belongs to Ceasar and give onto God what belongs to God. Socialists want to give everything onto Ceasar because they've mistaken him for God.
Communism replaced God with the state.
One does not need to be religious to understand why this analogy is correct. In fact, Randian atheists will see the point as clearly as conservative Christians.