Now this I say and testify in the Lord, that you must no longer walk as the Gentiles do, in the futility of their minds. They are darkened in their understanding, alienated from the life of God because of the ignorance that is in them, due to their hardness of heart. They have become callous and have given themselves up to sensuality, greedy to practice every kind of impurity. But that is not the way you learned Christ! — assuming that you have heard about him and were taught in him, as the truth is in Jesus, to put off your old self, which belongs to your former manner of life and is corrupt through deceitful desires, and to be renewed in the spirit of your minds, and to put on the new self, created after the likeness of God in true righteousness and holiness. Ephesians 4:17–24, ESV
The writers of the New Testament had no concept of a Christian whom many today would call a “Carnal Christian.” All believers still sin in this life and there will be times when they struggle with certain sins as if in a deadly battle, which they perceive as one they are losing. However, God will not leave His children this way. There will be no peace in the heart of a genuine Christian who is actively indulging his or her flesh. Instead, there will be heartache, self-loathing, and a deep desire to get the victory and draw closer to the Saviour much as David did when finally confronted about his horrible sin of adultery with Bathsheba and the murder of her husband. There is no true peace in the heart of Christian who is hiding his or her sin. Those around them may not know what is going on, but God does and so do those hiding their sin. It is not a spiritually healthy situation.