The answer to our question depends on who you ask. Many people in the religious world give conflicting answers to this question. Why? Unfortunately, many must go to their creeds or doctrinal teachings to locate the answer. We will endeavor to answer it by consulting the Bible-God's answer book.
One who is born again. "Since you have purified your souls in obeying the truth through the Spirit in sincere love of the brethren, love one another fervently with a pure heart, having been born again, not of corruptible seed but incorruptible, through the word of God which lives and abides forever." {1 Peter 1:22,23} Christians must be spiritually born to enter God's family. Under Moses' law, those who were born of Jewish parents were automatically children of God. Yet, our Lord taught that unless one is "born again" he cannot enter God's kingdom {John 3:3-5}.
One who wears Christ's name. "And when he had found him, he brought him to Antioch. So it was that for a whole year they assembled with the church and taught a great many people. And the disciples were first called Christians in Antioch." {Acts 11:26} Members of God's family wear Christ's name. Those who obey the gospel of Christ confess their belief in Christ's Deity-He is the Master of our souls. Why would one who belongs to Christ wear any other name?
One who is growing spiritually. "But solid food belongs to those who are of full age, that is, those who by reason of use have their senses exercised to discern both good and evil." {Hebrews 5:14} Believers must continue to grow and mature spiritually. Peter told us we "must grow in the grace and knowledge of the Lord." {2 Peter 3:18} We desire God's word to help us grow into more "perfect" people {Matthew 5:6; 1 Peter 2:2}. God expects us to bear spiritual fruit by growing in our desire and ability to teach others the gospel. Sadly, many of God's children remain spiritual infants because they lack desire for real spiritual food that can lead them to maturity.
One who has the proper character. "Let your light so shine before men, that they may see your good works and glorify your Father in heaven." {Matthew 5:16} "A new commandment I give to you, that you love one another; as I have loved you, that you also love one another. By this all will know that you are My disciples, if you have love for one another." {John 13:34,35} God's people march to the beat of a different drum. They have different goals, are spiritual-minded, and seek to influence the world for the cause of Christ. Christians are people with godly character. Read very carefully the words of Peter in 2 Peter 1:5-11-the things God's people must add to their faith. God expects His children to be different in an ungodly world {Romans 12:1,2}. We must be holy as our Father in heaven is holy {1 Peter 1:15,16}.
The world may have difficulty accepting or understanding this answer. Sadly, their definition of a Christian may not be the same as God's. Men may think they have the correct answer, but God views the matter differently. If one wishes to be a Christian, he must look to the One who defined Christianity.