Recently, President Obama has been called a Socialist. Quadrilateral Thoughts says that calling someone a Socialist when they really aren't is "labelism," a good term, and one which describes a phenomenon that is all too common. (The post is about other labels, too, not just socialism.)
It is sometimes said that the early church practiced socialism, or communism. See Acts 4:32. Was this socialism? Very close, or really socialism, if you allow that there was some central church government (which isn't clear, at least to me -- maybe there was, and maybe there wasn't). I have heard, and even taught, that this is not binding on Christians today, because Acts 4 is describing a special circumstance, when many new Christians, who had come to Jerusalem for the Passover, become converted, and stayed on, were away from their normal means of making a living, in Galilee, or in other countries which were several days travel from Judea. At any rate, I don't practice Acts 4:32 fully, and neither does my church, or my denomination, nor am I aware of any congregation that does. And many conservative Christians are strongly opposed to socialism, or anything even close to it.
Acts 4:32 is apparently the fulfillment of Luke 12:33 (I have linked to the Blueletter Bible. Scroll down to see verse 33, which is shown in more than one translation, so as to present as clear a picture of the meaning as possible.) I confess that, in spite of reading the Bible many times, I hadn't paid attention to that verse, which says, in the ESV:
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Addendum, April 9, 2010
As Weekend Fisher points out in a comment, Peter seems to have kept his boat and fishing equipment. It occurred to me, after writing this, that some members of the early church kept their homes, because Paul or Peter stayed in them, or a new church began meeting in them. So either Christ wasn't demanding that all of us sell all of our possessions and give the result to charity, or the early church didn't follow His commandment.
Nonetheless, I'm afraid that I, and most Christians, take having things too seriously, and Christ's command to help the poor not seriously enough.