What is a Christian? One who, by the grace of God, can declare that he justly deserves the wrath of God, save for the mercy of Jesus Christ alone. He casts aside all hope in his self-righteousness and puts away all pride in his own goodness. One who is glad to be regarded as spiritually bankrupt, a poor sinner, saved by the free grace and righteousness of Christ and, with a renewed heart, yields in allegiance to Him alone as LORD and sovereign. In a word, one who "glories in Christ Jesus and has no confidence in the flesh." (Phil. 3:3)
To be a Christian, is to be in Christ ... to be forgiven and granted a place at His table. We affirm salvation is by Christ alone - its all of grace. Good will, works, obedience and merit add nothing to our just standing before God (Rom 9:16; Gal 3:3; Eph 2:9). Neither these nor anything else can help us attain or maintain our just standing before God. Obedience flows from the cross, it does not contribute to it. It is a fruit of our union with Christ not the root. We obey, because we are saved, not in order to attain or maintain our just standing before God (that is Christ's office, and His alone). It only as we are joined to Christ by the Holy Spirit that we have life... that the power of sin is broken and we are declared righteous in His sight - and all our sins, both now and forever are forgiven on account of His name alone. AMEN
A Christian, then, is one who is called by God, and by the grace of God has been made a disciple, a follower of Christ and one who clings to the gospel. Furthermore, a Christian is one who is prepared to suffer for the sake of Christ, if God so ordains it.-- Monergism.