So leaving aside those who want to cling to canonical Mark as a jilted girl pines for her dishonest lover we return to the problem of Colossians 2:15.
So the assumption seems to be that the body or the flesh = the worldly powers. Where does that come from exactly? Well clearly in various gnostic schools the angels made Adam after the image of the Perfect Man. The classic or earliest surviving preservation of this understanding is found in the Apocryphon of John:
And he said to the authorities which attend him, 'Come, let us create a man according to the image of God and according to our likeness, that his image may become a light for us.' And they created by means of their respective powers in correspondence with the characteristics which were given. And each authority supplied a characteristic in the form of the image which he had seen in its natural (form). He created a being according to the likeness of the first, perfect Man. And they said, 'Let us call him Adam, that his name may become a power of light for us.'
"And the powers began: the first one, goodness, created a bone-soul; and the second, foreknowledge, created a sinew-soul; the third, divinity, created a flesh-soul; and the fourth, the lordship, created a marrow-soul; the fifth, kingdom created a blood-soul; the sixth, envy, created a skin-soul; the seventh, understanding, created a hair-soul. And the multitude of the angels attended him and they received from the powers the seven substances of the natural (form) in order to create the proportions of the limbs and the proportion of the rump and the proper working together of each of the parts.
"The first one began to create the head. Eteraphaope-Abron created his head; Meniggesstroeth created the brain; Asterechme (created) the right eye; Thaspomocha, the left eye; Yeronumos, the right ear; Bissoum, the left ear; Akioreim, the nose; Banen-Ephroum, the lips; Amen, the teeth; Ibikan, the molars; Basiliademe, the tonsils; Achcha, the uvula; Adaban, the neck; Chaaman, the vertebrae; Dearcho, the throat; Tebar, the right shoulder; [...], the left shoulder; Mniarcon, the right elbow; [...], the left elbow; Abitrion, the right underarm; Evanthen, the left underarm; Krys, the right hand; Beluai, the left hand; Treneu, the fingers of the right hand; Balbel, the fingers of the left hand; Kriman, the nails of the hands; Astrops, the right breast; Barroph, the left breast; Baoum, the right shoulder joint; Ararim, the left shoulder joint; Areche, the belly; Phthave, the navel; Senaphim, the abdomen; Arachethopi, the right ribs; Zabedo, the left ribs; Barias, the right hip; Phnouth the left hip; Abenlenarchei, the marrow; Chnoumeninorin, the bones; Gesole, the stomach; Agromauna, the heart; Bano, the lungs; Sostrapal, the liver; Anesimalar, the spleen; Thopithro, the intestines; Biblo, the kidneys; Roeror, the sinews; Taphreo, the spine of the body; Ipouspoboba, the veins; Bineborin, the arteries; Atoimenpsephei, theirs are the breaths which are in all the limbs; Entholleia, all the flesh; Bedouk, the right buttock (?); Arabeei, the left penis; Eilo, the testicles; Sorma, the genitals; Gorma-Kaiochlabar, the right thigh; Nebrith, the left thigh; Pserem, the kidneys of the right leg; Asaklas, the left kidney; Ormaoth, the right leg; Emenun, the left leg; Knyx, the right shin-bone; Tupelon, the left shin-bone; Achiel, the right knee; Phnene, the left knee; Phiouthrom, the right foot; Boabel, its toes; Trachoun, the left foot; Phikna, its toes; Miamai, the nails of the feet; Labernioum - .
"And those who were appointed over all of these are: Zathoth, Armas, Kalila, Jabel, (Sabaoth, Cain, Abel). And those who are particularly active in the limbs (are) the head Diolimodraza, the neck Yammeax, the right shoulder Yakouib, the left shoulder Verton, the right hand Oudidi, the left one Arbao, the fingers of the right hand Lampno, the fingers of the left hand Leekaphar, the right breast Barbar, the left breast Imae, the chest Pisandriaptes, the right shoulder joint Koade, the left shoulder joint Odeor, the right ribs Asphixix, the left ribs Synogchouta, the belly Arouph, the womb Sabalo, the right thigh Charcharb, the left thigh Chthaon, all the genitals Bathinoth, the right leg Choux, the left leg Charcha, the right shin-bone Aroer, the left shin-bone Toechtha, the right knee Aol, the left knee Charaner, the right foot Bastan, its toes Archentechtha, the left foot Marephnounth, its toes Abrana.
"Seven have power over all of these: Michael, Ouriel, Asmenedas, Saphasatoel, Aarmouriam, Richram, Amiorps. And the ones who are in charge over the senses (are) Archendekta; and he who is in charge over the receptions (is) Deitharbathas; and he who is in charge over the imagination (is) Oummaa; and he who is over the composition Aachiaram, and he who is over the whole impulse Riaramnacho.
"And the origin of the demons which are in the whole body is determined to be four: heat, cold, wetness, and dryness. And the mother of all of them is matter. And he who reigns over the heat (is) Phloxopha; and he who reigns over the cold is Oroorrothos; and he who reigns over what is dry (is) Erimacho; and he who reigns over the wetness (is) Athuro. And the mother of all of these, Onorthochrasaei, stands in their midst, since she is illimitable, and she mixes with all of them. And she is truly matter, for they are nourished by her.
"The four chief demons are: Ephememphi, who belongs to pleasure, Yoko, who belongs to desire, Nenentophni, who belongs to grief, Blaomen, who belongs to fear. And the mother of them all is Aesthesis-Ouch-Epi-Ptoe. And from the four demons passions came forth. And from grief (came) envy, jealousy, distress, trouble, pain, callousness, anxiety, mourning, etc. And from pleasure much wickedness arises, and empty pride, and similar things. And from desire (comes) anger, wrath, and bitterness, and bitter passion, and unsatedness, and similar things. And from fear (comes) dread, fawning, agony, and shame. All of these are like useful things as well as evil things. But the insight into their true (character) is Anaro, who is the head of the material soul, for it belongs with the seven senses, Ouch-Epi-Ptoe.
"This is the number of the angels: together they are 365. They all worked on it until, limb for limb, the natural and the material body was completed by them. Now there are other ones in charge over the remaining passions whom I did not mention to you. But if you wish to know them, it is written in the book of Zoroaster. And all the angels and demons worked until they had constructed the natural body. And their product was completely inactive and motionless for a long time
But the Marcionite understanding is surely a lot simpler than this. We have to go back to his understanding of matter. Ephraem is deliberately evasive but we can assume that the basic formulation is identical with the other gnostic systems: 'Marcion said concerning the holy one[?] that he saw a certain image; and we shall not speak of these other things that follow' (PR1. 69, 45–70,2) In other words the image was Christ and Adam was made in his likeness out of matter.
But what about the idea of 'stripping off' the flesh? I think McGowan gets close to the right answer when he suggests that there is a consistent pattern within Marcionism and other early strands of Christianity that material things are seen to be the property of the ruler of this world - a concept not entirely divorced from the Roman hegemony.
To this end, the 'powers' made Adam out of one substance - hyle - but Jesus is preparing his initiates for the coming of a new kingdom by refashioning them out of another heavenly substance.