The Spiritual life has escaped corruption (death) the physical life doesn't escape destruction. We all die unless we are alive when the Lord returns. Peter is again speaking in terms of the Spiritual life of the believer. Everyone who recives the Lord Jesus as saviour partakes in the precious promise of eternal life with God the Father, will not die the second death, and has in them the new Spiritual life (nature) but they also retain the old flesh the Old Nature and it's lust. The believer escapes the corruption (death) that the unbeliever will suffer in eternity, that being the second death.1)John 11:26 And whosoever liveth and believeth in me shall never die. Believest thou this?
So there is no loss of fellowship. Unless you do not believe the Lord.
First on must define which of the seven deaths this is speaking of. We know it isn't physical because believers do die physically, once you are born Spiritually you never die Spiritually again. Now let's put the preceeding and the following verse for context, 24Martha saith unto him, I know that he shall rise again in the resurrection at the last day.
25Jesus said unto her, I am the resurrection, and the life: he that believeth in me, though he were dead, yet shall he live: Those who believe on the Lord Jesus Christ becom Spiritually alive, and we will be ressurected if we die prior to the Lords return. While our physical body is dead and buried we are alive in heaven, both the Soul and Spirit live with God. Paul says to be absent from the body is to be present with the Lord. So the Soul and Spirit of the believer are living if they have suffered physical death.
26And whosoever liveth and believeth in me shall never die. Believest thou this? So those who believe on Christ will never die Spiritually nor will they die the second death. So yes a believer can die the Temporal death, lose of fellowship. 1 John 1:9 "If we confess our sins HE is faithful and just to forgive us our sins and cleanse us from all unrighteousness" We must confess to restore fellowship. God will not hear any prayer from a believer if they haven't confessed their sin, the first thing any believer must do is confess their sin. James 4: 1 "From whence come wars and fightings among you? come they not hence, even of your lusts that war in your members?
2Ye lust, and have not: ye kill, and desire to have, and cannot obtain: ye fight and war, yet ye have not, because ye ask not.
3Ye ask, and receive not, because ye ask amiss, that ye may consume it upon your lusts.
4Ye adulterers and adulteresses, know ye not that the friendship of the world is enmity with God? whosoever therefore will be a friend of the world is the enemy of God.
5Do ye think that the scripture saith in vain, The spirit that dwelleth in us lusteth to envy?
6But he giveth more grace. Wherefore he saith, God resisteth the proud, but giveth grace unto the humble.
7Submit yourselves therefore to God. Resist the devil, and he will flee from you.
8Draw nigh to God, and he will draw nigh to you. Cleanse your hands, ye sinners; and purify your hearts, ye double minded.
9Be afflicted, and mourn, and weep: let your laughter be turned to mourning, and your joy to heaviness.
10Humble yourselves in the sight of the Lord, and he shall lift you up.
The lust and sin comes from the Old Sin Nature and when you have sin dominating your life you ask amiss unto you humble yourself in the sight of the Lord (i.e. you confess sin). Then He will lift you up, until you do that you have temporarily lost fellowship and temprarily lost the filling of the Holy spirit. The Holy spirit still indwells you, but He no longer controls you when you have unconfessed sin in your life.
2)Second a Christian cannot turn to live in sin or as you are trying to call it carnal state.
Whosoever is born of God doth not commit (practice) sin; for his seed remaineth in him: and he cannot (practice) sin, because he is born of God. They do not continue to practice sin, that doesn't mean that they don't sin and it doesn't mean they have no Old Sin Nature. However a person can turn from sin at salvation believe on Christ and then go back to a life of sin.
Unless again you don't believe the Lord.
So you want to throw out most of the New Testament teachings of Paul, especially when it comes to teaching of eternal rewards.
1 Corinthians 3:
1And I, brethren, could not speak unto you as unto spiritual, but as unto carnal, even as unto babes in Christ.
2I have fed you with milk, and not with meat: for hitherto ye were not able to bear it, neither yet now are ye able.
3For ye are yet carnal: for whereas there is among you envying, and strife, and divisions, are ye not carnal, and walk as men?
4For while one saith, I am of Paul; and another, I am of Apollos; are ye not carnal?
5Who then is Paul, and who is Apollos, but ministers by whom ye believed, even as the Lord gave to every man?
6I have planted, Apollos watered; but God gave the increase.
7So then neither is he that planteth any thing, neither he that watereth; but God that giveth the increase.
8Now he that planteth and he that watereth are one: and every man shall receive his own reward according to his own labour.
9For we are labourers together with God: ye are God's husbandry, ye are God's building.
10According to the grace of God which is given unto me, as a wise masterbuilder, I have laid the foundation, and another buildeth thereon. But let every man take heed how he buildeth thereupon.
11For other foundation can no man lay than that is laid, which is Jesus Christ.
12Now if any man build upon this foundation gold, silver, precious stones, wood, hay, stubble;
13Every man's work shall be made manifest: for the day shall declare it, because it shall be revealed by fire; and the fire shall try every man's work of what sort it is.
14If any man's work abide which he hath built thereupon, he shall receive a reward.
15If any man's work shall be burned, he shall suffer loss: but he himself shall be saved; yet so as by fire.
17If any man defile the temple of God, him shall God destroy; for the temple of God is holy, which temple ye are.
At some point when a believer has continued in sin long enough and only God knows that point God will allow them to die the sin unto death.
1 COrithians 5: 4 In the name of our Lord Jesus Christ, when ye are gathered together, and my spirit, with the power of our Lord Jesus Christ,
5To deliver such an one unto Satan for the destruction of the flesh, that the spirit may be saved in the day of the Lord Jesus.
The believer turned over to Satan for destruction of the flesh but the Spirit is saved in the DAy of The Lord. That person though taken out of this life by the sin unto death has their Spiritual life intact. Again you want to through out all of Paul's teaching or discount what he is saying to fit your theology. It simply doesn't fit.
3)2Peter 1:4 Whereby are given unto us exceeding great and precious promises: that by these ye might be partakers of the divine nature, having escaped the corruption that is in the world through lust.
So the new nature does not simply reside in the Spirit but we actually become partakers of that nature. There is no old nature. The only thing left is the flesh to battle.
Again you must define which death is spoken of and if you get that wrong then your theology is off.