Christianity is not a religion. It is the revelation of God in human history through Christ.
Sorry, you don't get to re-write the definition of words to help your argument. From www.websters.com:
re·li·gion
1. a set of beliefs concerning the cause, nature, and purpose of the universe, esp. when considered as the creation of a superhuman agency or agencies, usually involving devotional and ritual observances, and often containing a moral code governing the conduct of human affairs.
2. a specific fundamental set of beliefs and practices generally agreed upon by a number of persons or sects: the Christian religion; the Buddhist religion.
Christianity is clearly a religion. Interestingly, you could define the Bible itself as a "revelation of God in human history through Christ". I wouldn't believe it to be true of course...but given a different set of core assumptions, it would be a valid definition.