(Romans 8:9) “But ye are not in the flesh, but in the Spirit, if so be that the Spirit of God dwell in you. Now if any man have not the Spirit of Christ, he is none of his.”
Would you say a Christian is a person who has a personal relationship with God through Christ? Well, while it is true that they do, it is true that the lost also have a personal relationship with Him. It may be a terribly dangerous one, but a personal relationship non the less. What separates the natural (lost) man from the Spiritual (saved) man, is the indwelling of the Spirit of God. A Christian is Somebody living in somebody! The Holy Spirit living in me! Him (The Spirit of Christ) living out His life in and through me! If you call your self a “Christian” and that is not taking place, you may need to reevaluate.
(Galatians 2:20) “I am crucified with Christ: nevertheless I live; yet not I, but Christ liveth in me: and the life which I now live in the flesh I live by the faith of the Son of God, who loved me, and gave himself for me.”