Carnal Christianity - sounded like an oxymoron to me - and knowing that The Word is, as it should be, our only authority I began my search.

The church of Corinth is commonly cited as proof that even Carnal Christians are saved and on their way to heaven. The primary passages in question are..

And I, brethren, could not speak unto you as unto spiritual, but as unto carnal, even as unto babes in Christ. I have fed you with milk, and not with meat: for hitherto ye were not able to bear it, neither yet now are ye able. For ye are yet carnal: for whereas there is among you envying, and strife, and divisions, are ye not carnal, and walk as men? For while one saith, I am of Paul; and another, I am of Apollos; are ye not carnal? 1 Corinthians 3:1-4

Is Paul talking carnal Christians here?  Ernest C Reisinger of PeaceMakers thinks not:

“A passage of Scripture must never be used as a foundation for a doctrine unless that passage is specifically dealing with that doctrine. Most certainly a non-doctrinal passage cannot be used to contradict a passage where that specific doctrine is the subject of discussion. 1 Corinthians 3 is not a doctrinal passage and by no stretch of the imagination can it be thought of as providing the foundation of the doctrine of sanctification. Yet this is exactly what the Carnal Christian advocates do with these verses. An examination of Romans 8, where security and sanctification are the subjects being dealt with, will show what happens to every person who is dominated by carnality…"

If you have one Scripture only on which to base an important doctrine or teaching you are most likely to find, on close examination, that you have none'. In short, all Paul is saying in 1 Corinthians 3:1-4 is that, in some areas of their lives, Christians can and do sometimes act like the unconverted.

"But your iniquities have separated you from your God; and your sins have hidden His face from you, so that he will not hear". Isaiah 59:2

"For the wages of sin is death; but the gift of God is eternal life in Jesus Christ our Lord". Romans 6:23

Hmmm -- Carnal Christians believe that holiness which, although it might be both admirable and commendable, is not essential to salvation, and depends not on the commands of the Lord, but on the spiritual inclinations of the individual. They believe that they can have their cake and eat it too... living as they want in this world, then scrape through by the skin of their teeth. Although they will possibly lose some blessing in their present lives and certainly rewards in the kingdom to come, they will at least be there for all eternity.

Carnal Christianity implies a habitual state of carnality,  "however, you are not in the flesh but in the Spirit, if indeed the Spirit of God dwells in you But if anyone does not have the Spirit of Christ, he does not belong to Him….for if you are living according to the flesh, you must die; but if by the Spirit you are putting to death the deeds of the body, you will live. For all who are being led by the Spirit of God, these are sons of God. Romans 5:9, 13-14

As long as we are in our present bodies, sin will continue to be something we  battle daily. As Galatians 5:17 describes it.. "the flesh lusteth against the Spirit". Every Christian is carnal in some area of his life and his growth in Holiness is far from a smooth and easy ride. There are hills and plateaus, obstacles to be overcome and mountains to be scaled. However, through it all, the one thing that Christians do not do is deliberately and habitually sin. The Spirit has become the governing force in the born again Christian.

"Those who belong to Christ have crucified the sinful nature with its passions and desires." Galatians. 5:24

Lest anyone should think that being carnal is a place of safety- remember: 

The history of heresy shows that virtually all ‘other gospels’ have been based on Bible verses... twisted, manipulated and so wrenched from their context, that they can be made to prove almost anything the reader’s heart desires. And why worry about little details like the fact that all too often they flatly contradict other Biblical verses. salvation involves more than simply affirming in one’s mind that Jesus is LORD and Saviour. The modern day perversion of every aspect of the Gospel would lead us to believe a person is saved based solely on the fact that he has made a ‘decision’, walked an aisle, made a profession of faith, or asked Jesus to come into his heart.

Biblical salvation takes genuine repentance, which the Bible presents as being connected to salvation. Over and over again, the Bible divides men into two groups... the saved and the lost, the believer and the unbeliever, the sheep and the goats, the children of darkness and the children of light, etc. It is black and white, without even a suggestion of people having all the characteristics of people in the first group, yet all the benefits and blessings of those in the second.

Of which group are you?

For to be carnally minded is death; but to be spiritually minded is life and peace. Romans 8:6

thanks to inplainsite for the treasure trove of information