Before you use the adjective (or noun) Christian for anything or anybody, three conditions must apply to whatever you want to name.
A transcendent connection with God through faith in Jesus Christ. Transcendent means that its origin and meaning are from God, not from human imagination or will. We may accept it, believe it, live by it, or deny it, but it is not ours to originate or manage.
A moral commitment to the earthly welfare and eternal salvation of all people everywhere. As the connection is from God, so is the work of God in Christ that makes both earthly goodness and eternal life possible for us. Commitment to other people is ours to make. Without the commitment, no Christianity.
An intentional discipline of submission to the Bible, the Old and New Testaments, as the Word of God. Christianity is not only God's work, it is also God's idea. He has told it to us. We are required to hear it. This is a discipline, not an option.
These are not summaries of Christian theology, but a working description of what makes a person, organization, or activity Christian. All three must apply at the same time to the same entity. This runs counter to the spiritual trend of our time, which views God as an elective, and dissipates in the sand of perfectionism, beyond the capability of human flesh; or in the lazy comfort of pluralism, which grants equality to all religious concepts regardless of their origin or merit; or in a standard so low that the specificity of the Bible is lost, as follows:
- If one of the conditions apply, you are a Christian.
- If two of them apply, you are a saint, or "you must be a preacher."
- If all three of them apply, you are a religious nut—a fundamentalist maybe, or a Holy Roller, or even someone resembling the creepy assassin in The DaVinci Code.
Needless to say, I think the prevailing view is intellectually vapid. Christians and Christianity are real things, identifiable by their origins, their literature, their history, and their geography. This doesn't make Christians perfect in their connection with God, in their commitment to other people, or in their submission to the Word of God; but it ought to lead those who apply Christian to themselves to ask, "Do I have a transcendent connection with God through faith in Christ? Am I morally committed to other people, both for this world and the world to come? Do I submit to the Bible as the Word of God?"
This synthesis may be new to you in the way it is stated. If its content is new to you then you may not know the Bible or the history of Christianity as well as you thought.
The Bible, history, and personal experience converge on these conditions. All of them are necessary. You cannot choose between them and end up with anything that works. Not even two out of three will work.
On the practical, working, everyday level this is the Christian synthesis. It is not a matter of opinion. It just is.