Some of my friends have given up on the name Christian. I have not. I expect it to outlast me by several decades, if not centuries. It is actually pretty hard to kill a perfectly good word — as Christian is — especially when you don't have a substitute that will serve as well.
Take love as an instance. We accept it as a synonym for sexual intercourse, but also name it as the chief theological virtue: "There are three things that last forever, faith, hope, and love; and the greatest of these is love" (I Corinthians 13:13). Nobody claims we have to rename the virtue because the word is used in more than one way, but some believe that Christ's followers need to be renamed.
Christian is fine with me. It has lasted for a couple of millennia. There is no other word that covers so many historical and theological bases.
Like most words, it adapts to its context. It is a useful adjective, giving terms like Christian history, Christian ethics, Christian habits, Christian faith, etc., an agreed-upon frame of reference. A frame is not the picture, but it defines the physical or intellectual space it surrounds. Or, to change the metaphor, the frame of reference is the smithy, as it were, where precise meanings are hammered out.
As I write, it occurs to me that this column expands on "The Christian Synthesis," a column from 2007. You will find it in the PO archives.
Revelation, relationship, and responsibility are Christianity's frame of reference. From the human perspective Christianity is first of all a revelation, then a relationship, then a responsibility. It is not a form of recreation, though it is not hostile to recreation. Once in a while recreation is a pleasant, though unnecessary, by-product of Christianity.
Revelation means that Christianity comes into the world from outside of it. The Christian Bible is the written form of the revelation. Jesus of Nazareth, named in the Bible as "the Christ, the Son of the living God," is the human form of it, and "the household of faith, the church of the living God, the pillar and bulwark of the truth" is the living, contemporary expression of it.
God is revealed, not imaginary. Nobody thought him up. He has told us what he has done and what he is doing, and told us what to do.
Out of the revelation is established a relationship between God and those who become his children by faith.
The children of God are responsible persons, so when they cease to be Christians it is a dead certainty, literally, that at least one of these is the reason:
They have ceased to believe there was, or is, a revelation.
They have lost their relationship with God and/or other Christians.
They are tired of responsibility .
In short, they no longer want to be called Christians.
Their problem, though, is that they once believed that their faith was real, and there remains the niggling possibility that that was the time they had it right!
Belief is not an easy road, but unbelief is no easier.