There are many today who divide humanity into three categories: One is called the "natural man" (1 Cor.2:14) who is unsaved; the next is the "spiritual man" (1 Cor.2:15-16) who is a Christian; and the last is the "carnal man" (1 Cor.3:1-4) who say's he's a Christian but is not obedient to God. The problem with that interpretation is that it is not biblical. In fact it is out of harmony with the balance of Scripture. God commands every true believer to be obedient to His commands and be controlled by His Spirit (John 14:15; Eph.5:18; Col.3:16).
In Scripture, the words carnal and fleshly most often refer to unsaved people and not Christians. The carnal mind directly defies God (Rom.8:5-8), which is not characteristic of a true believer. Therefore to use the terms "carnal Christian" to refer to a true believer is a contradiction in terms.
There may be Christians who fall into sin and act carnally, but carnality is predominantly characterized by unbelievers, because they are total unable to place God (See Heb.11:6).
"If a person's life is not charactized by righteousness, the entire book of 1 John declares that he is not truly saved" (Grace to You, Winter, 1988, Vol.11, No.1). A person who has a disobedient nature is one who is not walking by the Spirit's control and therefore may not even possess the Spirit.
What then is carnality? Can a true believer be carnal? As we have already noted, Christians can fall into sin and act carnally. But to say that this is a permanent state for a Christian is not true. Think of it in these terms -- you are either filled with the Spirit or you're not. When you're not, then you are carnal. If carnality is a habit of your life rather than Christ's righteousness, then that gives evidence you were never saved (see 1 John 3). "A person who has no desire for obedience has no legitimate claim on salvation" (Ibid., Grace to You).