I agree with flpalermo on this, but would like to expand just a little. The word Christian was first given to the believers of Antioch and literally means, "Follower of Christ". In order to have the Spirit of Christ, Jesus said we must be "Born Again" (John ch 3). In Ephesians ch 2, we learn that we are saved by God's grace, through faith. The Spirit of God dwells in those who trust in Christ's finished work, his sacrifice on the cross and resurrection from the dead. This reconciles us to God, our Father, and gives us direct access to him, without any intercessor but Christ. We can approach God directly because when we are spiritually reborn, we become children of God. The Bible also teaches us that we can tell whether someone is a true or false Christian by their "fruit" (Matthew 7:16-20) and we know that the fruits of the Spirit are: love, joy, peace, longsuffering, gentleness, goodness, faith, meekness, temperance: (Galatians 5:22-23). So to me, a Christian is one who has trusted Christ to save them from sin and reconcile them to God, thereby being reborn by the Spirit of God. Those who do so are true Christians, and it will be obvious in their conduct toward others.