Romans 8:13 talks about living after the flesh and dying. Is this the experience of one who believed but stopped believing, or what is it?

This text is from a transcript of a talk by David Gooding, entitled ‘The Gospel of Jesus Christ’ (1994).

Well, if you take it as an experience of one who believed then stopped believing and, therefore, died, you will have to remember that you're using a term 'believing' in the sense that our Lord used it in the parable of a sower—those that believed for a while, but when testing came, they fell away because they had no root. They never did have any root. They weren't, in that sense true, genuine believers. John, the evangelist, has one or two places in his gospel where he himself makes that distinction. In chapter 8, Jesus said to those Jews who believed on him, 'If you continue, you shall be my disciples. You know the truth, and the truth shall make you free.' Five minutes after that he was telling them that they were, in fact, with their father the devil, and they were picking up stones to stone him. They said they had believed. In some sense, they had believed, but when put to the test they were found not to be believers at all but unregenerate children of the very devil.

I think the words are to be addressed to us as believers. If we live after the spirit, we shall live. If we live after the flesh, we shall die. Similarly, Paul says to the believers in Galatia, 'If you sow to the spirit, you will of the spirit reap eternal life. If you sow to the flesh, you will of the flesh reap corruption' (Galatians 6:8). I take it, therefore, in that modified sense we all, as believers, have eternal life. It's one thing to have life, it's another thing to give your energies, time, thought, your will, and everything else, to the Holy Spirit; in which case you will develop your eternal life and reap the investment of your time and energy, in the blooming and harvesting that eternal life makes possible. Investing your time in his word this afternoon will surely, by God's promise, reap its harvest. If, as believers, however, we sow to the flesh, we shall reap it—if not in tears and broken hearts here—yet shall we eternally feel the result of wasted years, of works possibly that will not survive the criticism of Christ, and shall be burned up, leaving ourselves saved, but our works burned up. Saved, so as by fire (1 Corinthians 3:15). The restrained term of Scripture is that such people will suffer loss. There are consequences. There is no penalty for a believer of sinning, and there's no condemnation, but there are consequences. Thank God there are consequences on both sides. Sow to the spirit and you reap the benefits of your eternal life in its development and harvest. Sow to the flesh and you'll reap, in that extended sense, death, corruption, loss and damage; and that loss could be eternal.