It is often said that 'Christian' can be defined as 'little Christ', meaning we are to be Christ-like, although that isn't really a complete definition (not that I don't agree with the idea.
The title 'Christians' is recorded in Acts as first being used by nonbelievers in Antioch to describe those who followed the Way, that is belonging to the Church. This title was given in explanation for the way the believers at the time acted, proving with actions they were followers of Christ.
This word, 'Christianos', can portray several different relationship of the believer to Christ.The termination '-ianos' found in this word seems to be a Latin term used throughout the Roman empire, even by the Greek speaking.
The term itself can mean several things, including a slave, a partisan, or a follower
Therefore, Christians are slaves to Christ, following the commandment and giving all of our own rights away to Christ.
Christians are partisans of Christ's way, adhering strongly to His teachings.
Christians are at the simplest, followers of Christ, which includes following His leading in daily life, just as the disciple would have with Him as rabbi.
Before this word was used, these people were labeled by various other titles. One of which being the Church, used by Christ himself when telling Peter that His (Christ's) Church would be built on rock, and gates of Hell would not prevail against it.
The word here, ekklessia, literally means 'called out or called forth"
Even with the variance in definition, one thing that we should be able to agree one is what a Christian isnt: someone who merely holds the title but does not perform the duty.