That is perhaps how it would appear from the writings of Paul, but that is not exactly what he was addressing. Paul was simply speaking with compassion and relaying their struggles and how to deal with them as if they were his own, or referring to such a time when they were his own...just as he also did saying, "
When I was a child, I spoke as a child, I understood as a child, I thought as a child; but when I became a man, I put away childish things."
1 Corinthians 13:11
But this rather is a statement revealing the times as being on the cusp of salvation having come to those who were even born before it had come. In this way, Paul was walking them out of the darkness and into the light, using himself as one to follow, even saying "
imitate me." In other words, the words were especially for that generation, but also for coming generations who would also hear the good news of Christ, and would perhaps need to wrestle with it in their own lives, as was and is common.
Again, this is an issue of misunderstanding the timing. The most common timing of salvation did and does take time--which is that time between hearing and believing to a point of laying down your life, that Christ might raise it up again. Even now, in spite of an equal number of passages of scripture which say that salvation is instantaneous ("
old things have passes away, all thing have become new" (past tense)), some still do not believe it is even possible until their flesh passes away of nature causes...as if salvation were by nature or by the flesh. It's not, but rather is by the spirit of God which began to be poured out upon all flesh beginning at Pentecost, "
each one in his own order."
So, no, the old man (of flesh) and the new man (of Spirit) do not wrestle. But some, by unbelief--not believing that salvation comes only to those who are dead to the flesh, continue to struggle. They struggle not with the new man, for they have refused Him--putting Him off, left to struggle with the old man. Thus, the promise remains only a promise, by their own unbelief.
But that is only part of what is true. In the case of the new man, those who do lay down their life giving it over to Christ, have died to self that Christ may live in them--for them "
to live is Christ", just as Paul also said. Which is to say, that they have been resurrected to new life in Christ--left alive (in spirit) but remaining in the world to finish the work of Christ during these times of the gentiles. These are those of which Paul wrote: "
those who are alive and remain." Which is not to say, those who are alive merely in the flesh, or have not received Christ in full, but remain in there own personal struggle with the flesh.
Which newness of life looks like a lie to those who have rejected the truth; but to those who fully believe, it is just as it was with Christ who took sin upon himself and walked among the dead (the first resurrection). Which is also that time of
reigning with Christ as Priests and Kings until the times are fulfilled.
Which things are not complete without the understanding that the resurrection of Christ in the flesh was a different event from that of His ascension. This is the confirmation and the foreshadowing of what I have just told you. "
First the natural, and afterward the spiritual." Two different events.
To those who fully believe and receive it, the first resurrection is to walk in this world in the carcass of their demise, which is service to God. However, as this is of God and not of the world, they do not wait until their flesh passes away to ascend, but have already ascended, just as they have already been crucified with Christ. Here, the forty days of Christ between His crucifixion and His ascension is a foreshadowing of two things which are not counted in time by God, but occur during the same time according to the times of this world: the times of the gentiles, and the reign of Christ for the gathering of the saints. Which is also that time of Satan being bound, and also loosed for a short time, until the times are fulfilled...those times foreshadowed by Noah and the forty days and nights of rain upon the earth, and by Jonah and Nineveh.