What is the biblical basis for Docetism? Docetism is the belief that Jesus never took a physical, corporeal form, but He was instead solely spiritual in nature. Passages such as 1 John 2:15,  Galatians 5:17, and Romans 7:18 could be construed to support their argument, but is there anything in the Bible that Docetists claim(ed) directly implies that Christ was not of flesh?

On another note, I'd also like to find documentation of a Docetist actually defending their belief with Scripture. Does anyone know of such a case or where I could find one?
INTRODUCTION

Docetism is the belief that Christ’s body was not human flesh.  This entails two teachings.  The first is that He only seemed to be human without real human substance (flesh).  Christ passed through Mary as water through a pipe without taking any substance from her.  They deny the nativity.  He just appears, perhaps out of her side, like a phantom might.  The second is that He may have been born and appeared with flesh of sorts, but His flesh was not real human flesh.  Instead it was made of star dust or of angel “flesh”.

Oddly to our ears perhaps it was that docetic belief against which those who believed Christ was born normally and as a human (God-man) had to overcome.  Christ was born normally in the normal fashion complete with blood, umbilical cord, and afterbirth.  In the end, the eternal virginity idea won out, but the question of how Christ was thus born in the flesh otherwise never quite got answered.

These heresies helped fashion orthodox Christologies, which also sprang out of the original question was Jesus born human in the flesh?  Was he adopted at his baptism?  Did he take flesh from Mary?  How does Son of Man and Son of God compute together?

REFERENCES

Tertullian tells us that those who believed such false things (denying Christ came in the flesh or born normally) did take their reasonings from scripture, but via alternations of words or excising of passages, if not books, of scripture.  Many are familiar with Marcion’s truncated roll of scripture (of the four gospels only Luke worked for him for example).  It was against that false compilation that the Muratorium canon appears.


  One man perverts the Scriptures with his hand, another their meaning by his exposition. For although Valentinus seems to use the entire volume, he has none the less laid violent hands on the truth only with a more cunning mind and skill than Marcion. Marcion expressly and openly used the knife, not the pen, since he made such an excision of the Scriptures as suited his own subject-matter. Valentinus, however, abstained from such excision, because he did not invent Scriptures to square with his own subject-matter, but adapted his matter to the Scriptures; and yet he took away more, and added more, by removing the proper meaning of every particular word, and adding fantastic arrangements of things which have no real existence.
  Anti-Marcion, Against Heretics, Chapter 38


Irenaeus about the same time gives us a hint about redefining words and comingling ideas.


  For [they maintain] [Valentinus, Marcion, etc] that the apostles intermingled the things of the law with the words of the Saviour; and that not the apostles alone, but even the Lord Himself, spoke as at one time from the Demiurge, at another from the intermediate place, and yet again from the Pleroma, but that they themselves, indubitably, unsulliedly, and purely, have knowledge of the hidden mystery;
  AH, Book III, Chapter II


And Irenaeus gives us another example of their reinterpreting or excising of John.


  
  John, however, does himself put this matter beyond all controversy on our part, when he says, “He was in this world, and the world was made by Him, and the world knew Him not. He came unto His own [things], and His own [people] received Him not.”  But according to Marcion, and those like him, neither was the world made by Him; nor did He come to His own things, but to those of another. And, according to certain of the Gnostics, this world was made by angels, and not by the Word of God. But according to the followers of Valentinus, the world was not made by Him, but by the Demiurge.
  AH, Book III, Chapter XI
  


Eusebius weighs in on the heresies, saying the same as Tertullian and Irenaeus had some 100 years earlier.


  
  They [Marcion, Valentinus, etc], indeed, use the Law and Prophets and Gospels, but interpret in their own way the utterances of the Sacred Scriptures. And they abuse Paul the apostle and reject his epistles, and do not accept even the Acts of the Apostles.
  Eusebius
  


Later circa CE 425 Theodoret picks out a few specific scriptures that the docetists change or ignore.


  For divine Scripture says that He was made man, not by mutation of the Godhead, but by assumption of human nature, of the seed of Abraham. This the divine Apostle openly says in the words “For verily He took not on Him the nature of angels, but He took on Him the seed of Abraham, wherefore in all things it behoved Him to be made like unto His brethren.” And again “Now to Abraham and his seed were the promises made: he saith not and to seeds, as of many; but as of one, and to thy seed, which is Christ.”
  These and similar passages have been cut out of divine Scripture by Simon, Basilides, Valentinus, Bardesanes, Marcion, and the man who is named after his maniacal heresy [Manes]. So they style the Master Christ God only, and describe Him as having nothing human about Him, but appearing in imagination and appearance as man to men.
  Letters


As to specific scriptures used by Docetists, most examples, as mentioned, revolve around His birth and of Mary and Joseph.

In this docetic interpretation of Christ being born not with human flesh from Mary, but with angel flesh, they point to various angelic appearances in support of their idea.


  Inasmuch as that which is born must undergo this nativity in order to become flesh [say the orthodox].  He [Christ] borrowed, they say [Marcion to Apelles], His flesh from the stars, and from the substances of the higher world. And they assert it for a certain principle, that a body without nativity is nothing to be astonished at, because it has been submitted to angels to appear even amongst ourselves in the flesh without the intervention of the womb.
  Tertullian, Against Marcion


Likewise, the Docetic will also reinterpret this passage of scripture about Jesus’ brothers and sisters.


  But whenever a dispute arises about the nativity, all who reject it as creating a presumption in favour of the reality of Christ’s flesh, wilfully deny that God Himself was born, on the ground that He asked, “Who is my mother, and who are my brethren?” Let, therefore, Apelles hear what was our answer to Marcion in that little work, in which we challenged his own (favourite) gospel to the proof, even that the material circumstances of that remark (of the Lord’s) should be considered.  First of all, nobody would have told Him that His mother and brethren were standing outside, if he were not certain both that He had a mother and brethren, and that they were the very persons whom he was then announcing,—who had either been known to him before, or were then and there discovered by him; although heretics have removed this passage from the gospel, because those who were admiring His doctrine said that His supposed father, Joseph the carpenter, and His mother Mary, and His brethren, and His sisters, were very well known to them.
  -ibid-


For Tertullian, the fact that Mary and Joseph had children, that Jesus had brothers and sisters was proof of the nativity and flesh of Christ; to assert no siblings was to deny that God Himself was born and born of human flesh.

CONCLUSION

So, Docetism falls into two categories.  One denies the birth of Christ with Christ merely appearing in phantom-like actions or as a phantom and the other allows for the birth from Mary, but as using angel flesh (star dust of a sort), rather than human flesh.  Both ideas appear at the time as a backlash against the thought of God appearing in bloody afterbirth after a very normal birth travail and Mary swaddling the new-born baby.


  For One who was to be truly a man, even unto death, it was necessary that He should be clothed with that flesh to which death belongs. Now that flesh to which death belongs is preceded by birth.
  –ibid-


Tertullian, Irenaeus, and others charge the docetists (Marcion, Valentinus, Apelles, etc) of either using a knife to cut-out scripture or a pen to reinterpret scripture.  There are discernible inferences to the reinterpreted scriptures and to the excised scriptures upon which Docetism was founded.  The concluding point is Docetism is not found in scripture, but to assert otherwise is simply to deny that Christ came in the flesh (2 John 1:7).