No one in the "three camp" can explain the purpose of a soul without a spirit, or a spirit without a soul. If you sever a head from a body, neither the head nor the body survives. It is a silly nonsensical view that provides no purpose except to create division within the body.
I agree that the soul and spirit are inextricably joined, but there is no way that the two are synonymous. As I have stated:
Whither the spirit goeth, the soul taggeth along
In certain passages, soul and spirit are seemingly used interchangeably because the spirit is the primary substance of the human. Therefore, it is completely rational to say that where the man is, his ego is also.
But, upon looking at certain passages in scripture, it becomes blatantly obvious that when speaking of the soul, it is no way speaking of the spirit or the flesh.
Leviticus 17:11 For the life of the flesh is in the blood, and I have given it to you on the altar to make atonement for your souls; for it is the blood by reason of the life that makes atonement.
This atonement was most certainly for their conscience. Because their sins had been "covered", their minds did not have to be burdened with guilt. Leviticus 5 deals with guilt offerings for individual sins.
Hebrews states:
Heb 9:8-10
The Holy Spirit is signifying this, that the way into the holy place has not yet been disclosed while the outer tabernacle is still standing, which is a symbol for the present time. Accordingly both gifts and sacrifices are offered which cannot make the worshiper perfect in conscience, since they relate only to food and drink and various washings, regulations for the body imposed until a time of reformation.
Heb 9:13-15
For if the blood of goats and bulls and the ashes of a heifer sprinkling those who have been defiled sanctify for the cleansing of the flesh, how much more will the blood of Christ, who through the eternal Spirit offered Himself without blemish to God, cleanse your conscience from dead works to serve the living God?
Heb 10:22
let us draw near with a sincere heart in full assurance of faith, having our hearts sprinkled clean from an evil conscience and our bodies washed with pure water.
The conscience can be clean only because the blood of Jesus washes away the sin from our spirit.
Hebrews 10:1-4
For the Law, since it has only a shadow of the good things to come and not the very form of things, can never, by the same sacrifices which they offer continually year by year, make perfect those who draw near. Otherwise, would they not have ceased to be offered, because the worshipers, having once been cleansed, would no longer have had consciousness of sins? But in those sacrifices there is a reminder of sins year by year. For it is impossible for the blood of bulls and goats to take away sins.
This is a total removal of sin, which is the essence of regeneration of the spirit. Saved by the washing of regeneration (Titus 3:5). The New Creation (2Cor 5:17-21) is dealing with the spirit:
Therefore if anyone is in Christ, he is a new creature; the old things passed away; behold, new things have come. Now all these things are from God, who reconciled us to Himself through Christ.....He made Him who knew no sin to be sin on our behalf, so that we might become the righteousness of God in Him.
However, the cleansing of the conscience happens when we are baptized:
1Peter 3:21
the patience of God kept waiting in the days of Noah, during the construction of the ark, in which a few, that is, eight persons, were brought safely through the water. Corresponding to that, baptism now saves you—not the removal of dirt from the flesh, but an appeal to God for a good conscience—through the resurrection of Jesus Christ
Romans 6:3-7
Or do you not know that all of us who have been baptized into Christ Jesus have been baptized into His death? Therefore we have been buried with Him through baptism into death, so that as Christ was raised from the dead through the glory of the Father, so we too might walk in newness of life. For if we have become united with Him in the likeness of His death, certainly we shall also be in the likeness of His resurrection, knowing this, that our old self was crucified with Him, in order that our body of sin might be done away with, so that we would no longer be slaves to sin; for he who has died is freed from sin.
Then, after this initial cleansing at baptism, there is an ongoing issue of experiencing a guilty conscience.
1John 1:9
If we confess our sins, He is faithful and righteous to forgive us our sins and to cleanse us from all unrighteousness
This is most certainly not speaking of cleansing the flesh, for it will continue in its current state until physical death. It cannot be speaking of the spirit being cleansed, for that happens at regeneration.
There is a three-fold cleansing:
the spirit is cleansed at regeneration. A new creation, new heart, new spirit, an
actual righteousness that goes far beyond justification. In justification, we are
viewed as righteous, whereas in regeneration, we
become the righteousness of God and are sealed forevermore from sin. According to 1John 3:5-9, the one who is born of God is not capable of sinning.
the soul is cleansed at baptism and many times after. We can walk in newness of life, not burdened by the failures of the flesh. Romans 6 Paul speaks of this newness of life, and in 714-25 tells how it works. It is no longer I, but sin in me, that is, in my flesh.
the body will be raised in a cleansed state
at the regeneration, or resurrection (Matt 19:28).
It is sown a perishable body, it is raised an imperishable body; it is sown in dishonor, it is raised in glory; it is sown in weakness, it is raised in power; it is sown a natural body, it is raised a spiritual body. If there is a natural body, there is also a spiritual body. (1Cor 15:42-44). When all the contrasts are taken as a whole, it becomes clear that this current body is sin-wrecked, but or resurrected body will be NOT sin-wrecked
There is much more. This is only a small treatment of how the spirit/soul/body are dealt with in the believer.
But mining through this issue also irons out the conflicted teachings of original sin compared with an age of accountability. It answers the issue of eternal security, the nature of the new creation as objective rather than subjective, and a whole lot.