What show Christianity be about? The word "Christ-ianity" have already defined it's meaning. It is not Biblianity (from the word bible), or Doctrinity, or Spirituanity. No! It's is all about Christ, not the Bible, not doctrine and not spirituality. It is Christ center and supreme. Paul puts it this way, "looking unto Jesus, the author and finisher of our faith," (Heb 12:2). The Christian faith begins and end with Jesus, it didn't include the many things we have added to it today. It is just Christ alone, it does not include a religious book (the Bible) because Christ is what we read and follow. A Christian is a follower, not a follower of the Bible or a believer of the Bible but of Christ. We believe and follow a living person, not some dead religious book.
Christianity does not include doctrine, for Christ is our doctrine. Christ is enough, we do not need some tradition, law's, rules, don't and do's etc. All we need is Christ and nothing else. When the early Church where having problem, there was the issue of what the Christian doctrine should be. The apostles wrote to these churches, trying to tell them what the Christian doctrine is, but in explaining the Christian doctrine the apostles wrote only about Christ. For example the church in Colosse where having serious doctrinal issues. A false doctrine was entering into the church.
This doctrine idolized angels and having visions, the doctrine emphasize on a lot of 'do not' - do not touch this, or do not eat this, or do not do this, say that etc. The doctrine was emphasizing on the sacredness of holy days like the Sabbath, new moon etc. The doctrine has a form of holiness and emphasize on abasing the body. Indeed there was serious doctrinal issues going on in the church in colosse and other surrounding churches. Paul was to write and address this issue but he did went ahead to start list what the Christian doctrine is, he didn't say, "women must cover their hair, they must not wear trouser or any man's cloth; you must go to church Ever Sunday because it is the Sabbath; you must read your Bible and try to be holy because God is holy..."
NO! NO! and NO! Paul didn't say anything like that, he simply told them who Christ is, the letter to the Colossian contains a mighty revelation of Christ. Paul was saying, "no! You are missing it, the Christian doctrine is not this or that, the Christian doctrine is a living person, it is Christ." The Christian doctrine is not a dead practice, it is Christ living through us. After Paul describe who Christ is in chapter one, then in chapter two he emphasize that they should focus on Christ and not those practices, philosophies and ideologies (or theologies and various interpretations of the Bible). In chapter three Paul revealed the our life is Christ and therefore the true Christian practice is practicing to live by Christ, to express Christ, to be conformed into the image of Christ through the knowledge of Christ.
Even John was to address certain doctrinal issues and then he wrote the Gospel of John and the first epistle of John. Both books simply talk about Jesus as the eternal life, the books wasn't about don't and do's. John was trying to say, "we do not get eternal life by doing this or doing that, the way to eternal life is not some practices, it is not a doctrine but it is a living person. Christ is the way to eternal life, he is the eternal life and he is the practice of eternal life". True Christianity had always been nothing else but Christ, it is Christ from start to finish nothing included.