So we have seen how the Christian and Greek spheres of existence could be seen (not that everyone saw it the same way - I am focusing on Paul's time and Paul's words.)
On of the writers that combines Jewish/Christian with Greek thought is Philo ("Mr Love") who was a direct contemporary of Paul and wrote many works which are considered almost proto-Christian - some later writers considered Philo WAS a Christian.
Now let's look at Philo's fascinating comments about Jacob's Ladder -
Jacob's Ladder is the Air
In Christian tradition, Jacob's Ladder is in heaven :
G.John 1:51 :
And he said to him, "Truly, truly, I say to you, you will see heaven opened, and the angels of God ascending and descending on the Son of Man."
But Philo specifically says Jacob's ladder is figuratively the Air - bridging the large interior space between Earth and Moon / Heaven :
Philo, On Dreams, 1st C. :
Very admirably therefore does Moses represent the Air under the figurative symbol of a ladder, as planted solidly in the earth and reaching up to heaven. For it comes to pass that the evaporations which are given forth by the earth becoming rarefied, are dissolved into air, so that the earth is the foundation and root of the air, and that the heaven is its head.
The ladder reaches from the Moon, it's head is in heaven :
Philo, On Dreams, 1st C. :
By the ladder in this thing, which is called the world, is figuratively understood the Air, the foundation of which is the earth, and the head is the heaven; for the large interior space, (which being extended in every direction, reaches from the orb of the moon, which is described as the most remote of the order in heaven, but the nearest to us by those who contemplate sublime objects, down to the earth, which is the lowest of such bodies,) is the air.
The Moon lies at the boundary of aether and air and combines them :
Philo, On Dreams, 1st C. :
Accordingly it is said that the moon is not an unadulterated consolidation of pure aether, as each of the other stars is, but is rather a combination of the aether-like and air-like essence. For the black spot which appears in it, which some call a face, is nothing else but the air mingled with it, which is by nature black, and which extends as far as heaven.
Later, Basil says Heaven is in the Air :
Basil the Great, Homilies, 4th C. :
"In the Firmament of Heaven," that is to say, as we have said before, in that part of the Air called heaven (ouranos), from the word oran, which means to see; called Firmament, because the air which extends over our heads, compared to the aether, has greater density,
From all this, we get a picture like so:
The Third Heaven
In Paul's time, there was reference specifically to Paradise in the Third Heaven -
The Life of Adam and Eve 11:1, 1st C. :
Then God spake to the archangel(s) Michael, (Gabriel, Uriel, and Raphael): 'Go away to Paradise in the Third Heaven, and strew linen clothes and cover the body of Adam and bring oil of the 'oil of fragrance' and pour it over him.
Perhaps such stories influenced Paul, who refers to BOTH 'paradise' and 'third heaven' in his famous passage -
2 Corinthians 12:2-4 :
I know a man in Christ who fourteen years ago was caught up to the Third Heaven. Whether it was in the body or out of the body I do not know—God knows. And I know that this man—whether in the body or apart from the body I do not know, but God knows— was caught up to Paradise. He heard inexpressible things, things that man is not permitted to tell.
Does this Third Heaven sound like the third of seven? Or the third of ten? No. This sounds like quite an accomplishment - this Third Heaven sounds like a high place.
I conclude that Paul's Third Heaven is the Heaven Above the firmament and that Paul sees the heavens like so :
3. The Heaven Above the Firmament
2. The Heaven of the Firmament
1. The Heaven Below the Firmament
Satan and spiritual forces of the Air
Christians saw Satan as being a power in the Air - this is clearly carried over from Greek beliefs about demons in the Air.
Many Christians quote the following passages :
Ephesians 2:2, 1st C. :
according to the prince of the power of the Air, the spirit that now worketh in the children of disobedience.
There is also Paul's comments about Christ being crucified by the "archons of the aeon" or the rulers of this age. This is widely seen to refer to spiritual rulers in the realm above the earth - i.e. the Air or the 1st Heaven.
These passages, and various others above help to confirm that the Christian Heaven Below the Firmament is essentially the same as the Air Beneath the Moon.
Flesh vs Spirit
Paul often uses a dichotomy of Flesh vs Spirit and this is much discussed. I think
Paul's Flesh---Spirit dichotomy,
is like the Greek Below--Above the Moon dichotomy,
and the Jewish/Christian Below--Above the Firmament dichotomy.
Combining all these ideas here, is what I think Paul saw as his Universe :
I have repeated the Flesh and Spirit to show how these divisions apply across multiple spheres - including how the 1st Heaven, the Heaven Below the Firmament, is within 'Flesh'.
The Vision of Isaiah.
There is a lengthy Christian work called the Vision of Isaiah which I won't quote here, but it has Isaiah ascending to heaven to be told of Christ's mission. He is told Christ's mission is to descend the heavens to be crucified. The text is notoriously corrupt in two versions but it appears that Christ descends only as far as the lowest heaven where he is crucified by the Prince of Power of the Air (Satan.)
Paul's view of the crucifixion :
Coupling the vision of Isaiah with Paul's words, I think Paul saw Christ crucifixion as occurring in the 1st Heaven (or the "Air" which was still within the realm of flesh, but not on earth. Like this diagram :
Note that Paul's journey mirrors Christ's.
This is why I am a Jesus mythicist - I think Paul originally wrote about a being who was crucified in a lower heaven, not on earth - but his words are unclear and obtuse. Later, others came to write stories about a historical Jesus, and they were believed.