Yes, it is an oxymoron. Christianity and Objectivism are two completely different systems. In Objectivism, reason is an absolute and rejects all forms of mysticism (belief in the unknown). Also, it is pro-selfishness, in Christianity you can't do something simply because it makes you happy, you have to do because it makes God happy. To call yourself an Objectivist or a Christian or a Socialist, etc., you have to follow the core principles. That being said there are people who call themselves Christians and believe in God, but also rely heavily upon reason as a guide in their lives and agree with many aspects of Objectivism.
Hi, I'm new here and I thought it'd be good to introduce myself. My name is Jennifer and I've been learning Objectivism for about 2 years now. I have read three of Ms. Rand's books so far: Atlas, The Virtue of Selfishness, and Anthem. Many times when I have searched for my questions a thread from this would be suggested, so I've decided to stop spying and become a member. Plus, I don't really have many outlets for discussion with others and able to feel very comfortable so why not give this place a shot.