What Changed?

Yes, Christians can backslide -- sometimes very seriously. But those occasions will be rare, for a true Christians CANNOT live in sin continually or indefinitely. Therefore, the true mark of a Christian cannot be carnal or worldly living. Such living is a mark of unbelievers.

Paul told his brethren they were carnal. What is the mark of a carnal Christian, Rufus?

I've explained that to you. A "carnal or worldly Christian" is an oxymoron. Under the New Covenant, no true believer will remain in that state for very long. The better question would have been: What is the mark of unbelievers -- those who are OF this world, unlike true believers.

On the contrary, Paul said many had not developed much at all, and still needed to be instructed rather than becoming instructors.

You're conflating "true believer", ie those who walk after the spirit, with "Christian", which includes carnal believers who walk after the flesh. Obviously the two are not equivalent

Which many Christians are

So they are being faithful to their rebellious nature???

Is this what you are saying?

Wrong.

What you consider to be "your experience" is not validation.
This is a classic example of appealing to esoteric knowledge and this will be your undoing.

I live by the written Word of God, it is sufficient. You should too.

It's not simply experience. It's the experience the word of God evidences and speaks to concerning the experience of God's people.
I only shared because there exists more to a genuine relationship with God than you have experienced, and I would like you to know God more intimately. I'm not suggesting you aren't a Christian, or that myself or others who have experienced God in more and varied ways are better or more Christian than you. Only that there is more of God to know.

You are simply talking in circles. Can you not see this?
Is your desire to share this based on a personal experience or the Word of God? What will I have to "experience" to know that I am knowing God more intimately?
If I am correct, you present yourself as one of the chosen few for salvation. Is this based on scripture, experience or esoteric knowledge?
Your belief that you are personally chosen or destined by God does not validate your experiences.

I agree but claiming individual experiences is esoteric by nature.

Anyone who is saved is chosen of God. And God hasn't chosen few. The promise to Abraham was as the stars in the sky and the grains of sand on the shore. Revelation 7:9 describes a number that no man can number. That hardly makes me one of a few.
And the experience I'm referring to is that which the Bible speaks of. An example is found in Ephesians 4. God gave different offices in the church so that the church would grow...till we all come in the unity of the faith, and of the knowledge of the Son of God...
The unity of the faith is concerning doctrine. That is, what the Bible teaches. The knowledge of the Son of God is experiential knowledge wherein one experiences the truth of the doctrine for themselves.
Perhaps some examples will help. Have you ever read a passage of scripture and later been meditating on it and God opens your understanding and you understand more fully what the passage entails. It was always true, yet your understanding was lacking. Now it is not. Just as Jesus opened the understanding of those men on the road to Emmaus, He came to you and did the same thing. This is an example of knowledge of the Son of God.
I could spend the day enumerating example after example of this, and am happy to share more if you like. But it is this knowledge of the Son of God that Paul gives as his reason for counting all things as loss...Philippians 3:8. And no doubt it has been the motivation behind many of the lives of saints throughout history.
So I'm not purporting esoteric experiences disengaged from the authority of scripture. I'm merely reporting what the Bible says is true of Christian experience.

Agreed.
Certainly not! Are you not aware of Matthew 22:14?

“For many are invited, but few are chosen.”

Are you not aware of Matthew 7:13-14?

“Enter through the narrow gate. For wide is the gate and broad is the road that leads to destruction, and many enter through it. 14 But small is the gate and narrow the road that leads to life, and only a few find it.

God has most certainly chosen only a few. Are you truly unaware of this?
This is a turn of a phrase and can not be used to negate the above scriptures. Your use of Genesis 26:4 is not even germane to the subject. Do you have a background in the Universalist Church? They use this verse a lot.
Personal experiences or insights are subjective by nature and hold no weight to another. Your personal experiences maybe right or wrong but it is certainly extra-biblical and should be taken with a grain of salt.

Most false doctrines are based on personal experiences or insights. Asking God to tell you if your experiences or insights are from Him is circular reasoning and best avoided. Instead we should follow the example of the Bereans. (Acts 17:11)

I greatly appreciate the discussion. Grace and peace.

To you also.

The Holy Spirit through Paul says th Corinthian Christians were carnal. In order to defend your religion, you are accusing the Holy Spirit of inspiring Paul to spout oxymorons, i.e. contradictions. I have good news for you. You can agree with scripture and have a deep abiding communion with Jesus Christ and the Godhead without forever dragging around the useless baggage of Calvinism. Take the opportunity to break free. You don't need Jesus AND some systematic theology.