According to what Apostle Paul taught in 2 Corinthians 5 and 1 Corinthians 15, our flesh body is a totally different dimension of existence than the "spiritual body". For this reason also, Lord Jesus showed in John 3 that which is born of the flesh is flesh, and that which is born of the Spirit is spirit. That is about two distinct and separate operations in two distinct and separate realms of existence.
1 Cor 15:42-54
42 So also is the resurrection of the dead. It is sown in corruption; it is raised in incorruption:
43 It is sown in dishonour; it is raised in glory: it is sown in weakness; it is raised in power:
44 It is sown a natural body; it is raised a spiritual body. There is a natural body, and there is a spiritual body.
The resurrection is about a "spiritual body", NOT a new flesh body, nor even the raising of our old flesh body. When our flesh dies we are done with it, forever.
45 And so it is written, The first man Adam was made a living soul; the last Adam was made a quickening spirit.
This above verse confirms what was just said. The first Adam means those born in the flesh. God puts our spirit into a flesh body and we becoming a living soul, meaning in the flesh. But the last Adam represents the final state 'without flesh', which is the state of a quickening spirit. Paul is referring again to the "spiritual body" by that, which he just covered in the previous verse.
46 Howbeit that was not first which is spiritual, but that which is natural; and afterward that which is spiritual.
We are first born into the flesh, which that "natural" represents the idea of flesh. But at death of the flesh, then the "spiritual body" manifests in that other dimension called the heavenly.
47 The first man is of the earth, earthy: the second man is the Lord from heaven.
Apostle John referring to our final state as the sons of God, said at present we don't know what we shall be, but when Jesus returns we know we will see Him as He is, and we shall be like Him (meaning with a spirit body similar to His, which is what Paul's "last Adam" idea represents).
48 As is the earthy, such are they also that are earthy: and as is the heavenly, such are they also that are heavenly.
49 And as we have borne the image of the earthy, we shall also bear the image of the heavenly.
In the above Paul makes this very, very plain and simple. As we have borne the image of the earthy, which is about our flesh body, we shall also bear the image of the heavenly, which is about the "spiritual body".
50 Now this I say, brethren, that flesh and blood cannot inherit the kingdom of God; neither doth corruption inherit incorruption.
And to make it even more plain for the knuckleheads out there, Paul proclaims strongly that flesh and blood cannot inherit God's Kingdom, just as a body of corruption (flesh) cannot inherit a body of incorruption (spiritual body). That goes back to what Lord Jesus said in John 3 that which is born of the flesh is flesh, and that which is born of the Spirit is spirit. In other words, flesh does not come from Spirit, and spirit does not come from the flesh. They are two separate and distinct operations.
51 Behold, I shew you a mystery; We shall not all sleep, but we shall all be changed,
52 In a moment, in the twinkling of an eye, at the last trump: for the trumpet shall sound, and the dead shall be raised incorruptible, and we shall be changed.
On the last day of this present world when Jesus comes on that "last trump" (7th), all those alive on earth will be 'changed' to the spiritual body at the twinkling of an eye (fast as you can blink an eye). A section of the Isaiah 25 chapter refers to this for ALL peoples, not just Christ's Church. Those of the resurrection are already in their spiritual bodies, as Jesus will bring those with Him when He comes (per 1 Thess.4).
53 For this corruptible must put on incorruption, and this mortal must put on immortality.
54 So when this corruptible shall have put on incorruption, and this mortal shall have put on immortality, then shall be brought to pass the saying that is written, Death is swallowed up in victory.
KJV
Paul quoted this from Isaiah 25 about death being swallowed up in victory. This reveals more as to what the Isaiah 25 Scripture was about with the vail being removed from all peoples on that day.
But Paul is covering 2 separate changes required to have eternal Life through Christ Jesus. We must put on the body of incorruption, which is the spiritual body, AND something else inside us that is liable to perish must put on immortality through Faith on Jesus Christ. That something else is about our soul.
The true Scripture definition of a 'soul' is not some flesh body idea from OT Scripture like Gen.2:7. The idea of becoming a 'living soul' is about God placing our spirit inside a flesh body, not animate spirit like plants have, but a spiritual body with a soul placed inside a flesh body. Our soul is our id or person, and it is always... attached to our spiritual body. Our spiritual body is simply our "image of the heavenly" that manifests when our flesh dies.
In 2 Cor.5, Apostle Paul taught that if our earthly tabernacle (house) were dissolved, then we still have a building not made with hands, meaning not of the flesh, but eternal in the heavens. He was speaking of the "spiritual body". You already... have it today, inside your flesh body. At flesh death it is loosed, which is what Solomon explained in Ecc.12:5-7 involving the "silver cord". We each have a "silver cord" that keeps our spiritual body with soul attached to our flesh body. At death it is severed. Our flesh then goes back to the earth where it came from, and our spirit (spiritual body with soul) goes back to God Who gave it.
So the idea that our dead loved ones are literally asleep in caskets in the ground is an old orthodox Jewish fable carried on even by some Christian Churches today. Our dead loved ones are in the heavenly, their "spiritual body" manifested already. That is how Jesus will bring those with Him when He comes as written in 1 Thess.4.