Christian [
http://dictionary.reference.com/search?q=christian]
adj.
1. Professing belief in Jesus as Christ or following the religion based on the life and teachings of Jesus.
2. Relating to or derived from Jesus or Jesus's teachings.
3. Manifesting the qualities or spirit of Jesus; Christlike.
4. Relating to or characteristic of Christianity or its adherents.
5. Showing a loving concern for others; humane.
n.
1. One who professes belief in Jesus as Christ or follows the religion based on the life and teachings of Jesus.
2. One who lives according to the teachings of Jesus.
---------------------------------------------------------------------------
[Middle English Cristen, from Old English cristen, from Latin Christianus, from Christus, Christ. See Christ. [
http://dictionary.reference.com/search?q=christ]
---------------------------------------------------------------------------
1 John 5:1 Whoever believes that Jesus is the Christ is born of God. Whoever loves the Father also loves the child who is born of him. 5:2 By this we know that we love the children of God, when we love God and keep his commandments. 5:3 For this is the love of God, that we keep his commandments. His commandments are not grievous.
So Jesus adhered to the commandments of the Father and that's why he was the Christ (Messiah). What is the law of the Father? The Mosaic Law. What is Jesus law? The Gospel accounts of Matthew, Mark, Luke and John contain them. The words spoken by the apostle Paul are also commandments from Jesus because Jesus revealed himself to Paul. Jesus' teachings are also represented by the apostle and disciple letters.
So what is a Christian? One that knows all of the laws in the scriptures, from old testament to new testament. One that knows which laws have been abolished. One that adhere's to all of the commandments that are left between the old testament and new testament. One that believe's the Jesus is the Messiah (Christ) and that God is one God and not three. One that professes this before people, that Jesus is the Christ sent by God. One that teaches other people the codes that Jesus believed in. For all of the previously mentioned is the makeup of "love thy neighbor as thyself" and "love God with your whole soul, mind and strength" which is the sum of the whole of the definition of a Christian.
James 5:19 My brethren, if any among you err from the truth, and one convert him; 5:20 let him know, that he who converteth a sinner from the error of his way shall save a soul from death, and shall cover a multitude of sins.
The scripture above also defines a Christian. That you save people by alerting them that they might be breaking commandments.