The Apostle here talks about our being away from the body and present with the Lord, not the resurrection. In the resurrection the body is raised, and transformed. Even as the Lord was raised and glorified in His flesh.
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But in fact Christ has been raised from the dead, the firstfruits of those who have fallen asleep. For as by a man came death, by a man has come also the resurrection of the dead. For as in Adam all die, so also in Christ shall all be made alive. But each in his own order: Christ the firstfruits, then at his coming those who belong to Christ. Then comes the end, when he delivers the kingdom to God the Father after destroying every rule and every authority and power." - 1 Corinthians 15:20-24
We will be changed at the last day, but if we die before then and go to heaven we will have to have a heavenly body. These bodies are for living on the earth, to live in time and space. Jesus is in his heaven in his heavenly body. These bodies came from the dust of the ground.
When the Lord returns in glory is when the dead rise,
bodily.
Even as the Lord was glorified in the resurrection, so shall we, as the Apostle writes in Romans,
"If the Spirit of him who raised Jesus from the dead dwells in you, he who raised Christ Jesus from the dead will also give life to your mortal bodies through his Spirit who dwells in you." - Romans 8:11
Which is why:
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So is it with the resurrection of the dead. What is sown is perishable; what is raised is imperishable. It is sown in dishonor; it is raised in glory. It is sown in weakness; it is raised in power. It is sown a soulish body; it is raised a spiritual body. If there is a soulish body, there is also a spiritual body. Thus it is written, 'The first man Adam became a living soul'; the last Adam became a life-giving spirit. But it is not the spiritual that is first but the soulish, and then the spiritual. The first man was from the earth, a man of dust; the second man is from heaven. As was the man of dust, so also are those who are of the dust, and as is the man of heaven, so also are those who are of heaven. Just as we have borne the image of the man of dust, we shall also bear the image of the man of heaven.
I tell you this, brothers: flesh and blood cannot inherit the kingdom of God, nor does the perishable inherit the imperishable. Behold! I tell you a mystery. We shall not all sleep, but we shall all be changed, in a moment, in the twinkling of an eye, at the last trumpet. For the trumpet will sound, and the dead will be raised imperishable, and we shall be changed. For this perishable must put on the imperishable, and this mortal must put on immortality. When the perishable puts on the imperishable, and the mortal puts on immortality, then shall come to pass the saying that is written:
'Death is swallowed up in victory.'
'O death, where is your victory? O death, where is your sting?'" - 1 Corinthians 15:42-55
And also:
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But our citizenship is in the heavens, and from it we await a Savior, the Lord Jesus Christ, who will transform our lowly body to be like His glorious body, by the power that enables Him even to subject all things to Himself." - Philippians 3:20-21
Understand that the Apostle does not mean that material flesh does not share in the life of the Age to Come, but that the present sinful, corruptible, mortal state cannot have a share in that future life, and so we look forward to the Lord's return, He who was raised in glorious, incorruptible, immortal flesh and who reigns at the right hand of the Father shall return, at which time we shall be raised like Him--in the body, physically, with the same glory, imperishability, and immortality.
We do not transform from "flesh" to "spirit", the transfiguration we receive in the resurrection is not a change from material to immaterial, but from a the sinful, soulish existence we have at present which we have received from Adam to the glorious, transformed existence which is of Christ.
"Flesh and blood" is an idiomatic expression. See its use
in other places.
Of course Christ is still flesh, because the Lord is a human being. He did not wear humanity like a vestment, but became really and truly human. If the Lord is a human being, then that matters. If He ceased to be human, if He ceased to have flesh then the resurrection is a sham, and our salvation is nothingness.
But Christ did rise from the dead, and He ascended and is seated at the right hand of the Father, and He will reign until the end when all things have been made subject to Him, and He returns in glory, death defeated when the dead are raised, and God makes all things new. This is our blessed hope. The resurrection of the body and the life everlasting.
The Apostles' Creed:
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I believe in God, the Father Almighty,
Maker of heaven and earth.
I believe in Jesus Christ, His only Son, our Lord,
Who was conceived by the Holy Spirit,
born of the Virgin Mary,
suffered under Pontius Pilate,
was crucified, died, and was buried;
He descended to the dead.
On the third day He rose again;
He ascended into the heavens,
is seated at the right hand of the Father,
and will come again to judge the living and the dead.
I believe in the Holy Spirit,
the holy catholic Church,
the communion of saints,
the forgiveness of sins,
the resurrection of the body*,
and the life everlasting. Amen."
*Original Latin is
carnis resurrectionem, literally, "the resurrection of flesh".
-CryptoLutheran