Were you to ask people What does it mean to be a Christian? or What are the minimal requirements for someone to qualify as a Christian? You could get any number of responses. Some common essential properties of being a Christian you might hear are:
A. Believes the Bible (Or some variation on in what way someone "believes the Bible.")
B. Goes to Church (For Catholics, I would enlarge this to include certain practices like eating fish on Fridays, etc.)
C. Believes "Jesus died for my sins."
D. Believes Jesus was/is God
E. Believes only Christians go to Heaven
F. Believes "You cannot make it to Heaven on your own."
G. Believes in the Resurrection
H. Is a member of my denomination
I. Believes God created the world in 6 days
(What answer would people you know give?)
It seems to me that most, if not all, the above have serious problems. For example, "E is self-referential...saying that a Christian is someone who believes that only Christians go to Heaven does nothing to define who a Christian is. If I believed I was a Christian and believed I was the only one going to Heaven, then "E" would apply to me...but yet I have done nothing to explain by that belief what it means to be a Christian.
Many of the above make no sense historically. We have to assume that the early apostles and their churches should count as "Christians," yet they did not have "The Bible," (indeed, the Church disagreed among itself for centuries as to which books belonged in the Bible and which did not) so one could hardly say that a requirement for Christianity is that you believe the Bible [though one could draw the conclusion that the Old Testament, at least, was accurate, as we see no account of Jesus suggesting otherwise.]
Similarly, the doctrine of atonement in its current state didn't even exist until the 11th century, and early believers did not have the trinitarian formulas the modern church holds so dear. Indeed, Origen, the most important Christian theologian of the 2nd century, would not even be allowed in the church today by that standard.
In addition to historical problems, significant biblical problems stand out from the above list as well. Where do we see early evangelists stressing to non-believers any of these things? If you want to see what makes a Christian a Christian, I think you should look at what the early apostles preached to non-Christians in an effort to have them join the Faith.
A study of acts can be rather revealing here. I've put together the following chart to illustrate what teachings you find in Acts regarding Christianity. I'm focusing on Acts because that is the only book where the focus is on Evangelism to non-believers and new believers.
go to Hell
|17: 2-4, 6-7||x||x||x|
Based on the above, I'd say that other than emphasizing the Resurrection, the church has rather struck out when it comes to defining who or what a Christian is.
It seems, at least if Paul, James, Peter, and Stephen are good sources, that a Christian is someone who has chosen to follow Christ's practices, repenting of unloving acts that God hates, and believes Jesus is the Christ (as shown by his Resurrection) who has been given power over Heaven and Earth, including the office of Judge.
While none of the above are things that most Christians would disagree with, they are also unlikely to be the first thing out of their mouths when asked What does it mean to be a Christian?
I think Christians in general do not like the idea that repentance is an absolute requirement as opposed to a goal. I would further say that merely believing Jesus is the Christ who sits in power over Heaven and Earth would strike many as "too easy," allowing too many fringe groups in. And in particular, the idea that "Christians, and only Christians, go to Heaven" is such a basic tenet to many that seeing it as not a required one just seems odd. The truth is that the word for Hell does not even show up in all of Acts. One wonders what that says about modern day evangelists and missionaries who start off their message with "Do you know where you are going when you die?"
But what do you think? What does it mean to be a Christian? Are there any passages you believe suggest there is some aspect fundamental to being a Christian that is missing from the message given by the apostles in Acts?