While He is the firstborn among many brethren, no, He cannot be a Christian in the sense that He was not born again, reliant on a Saviour, etc. It's like one of those things I think they ask student ministers in Bible Colleges... We could ask, "Is Jesus part of the Church?" - well, He is said to be the chief cornerstone, follwed by a foundation of apostles and prophets, etc., and yet the Church, as His Bride, is seen as a distinct entity to Him, yet vitally united to Him. It's all about definitions.
