What is a Christian?
Christianity : From Wikipedia 
Christianity is a monotheistic religion centered on Jesus of Nazareth and his life, death, resurrection, and teachings as presented in the New Testament. Christians believe Jesus is the Son of God and the Messiah prophesied in the Old Testament. 
Core features of Christianity include beliefs about:
- Monotheistic: Worshiping only one Deity.
- Jesus: The Wiki about the individual.
- The Bible: The Bible.
A Christian is one who pledges his/her allegiance to the God who took upon himself humanity (incarnation) made manifest in Jesus the Messiah/Christ, the one who not only defeated death through his being raised from the dead, but also triumphed over the power of evil/Satan in this world. Those who are followers of Jesus are called to love God with all their heart, mind, and strength and to love their neighbors as themselves. Jesus, while on Earth, told his followers to love one another 'even as I have loved you.'
The earliest writers to record the teachings of the first century Christian community were the Gospel writers: Mark (earliest Gospel), Matthew, Luke and, lastly, John. The most potent advocate of Christ's divinity and mission as saviour of sinners was the apostle Paul. He emphasised that anyone who believes that Christ died for him/her and repents of their sins is acknowledged [justified] by God the Father as without sin [cleansed through the blood of Christ]. This is also known as 'saving grace'. Another writer of the New Testament, James, emphasized that those who believe in salvation from Christ will act righteously, and that righteous action must accompany faith in order for the faith to be effective (James 2:17).
Being a Christian, then, requires having faith, and acting on it (by doing good deeds).
- Some non-Chistians see Christianity as polytheistic because of the three persons in the Holy Trinity.