Docetism was an error with several variations concerning the nature of Christ. Generally, it taught that Jesus only appeared to have a body, that he was not really incarnate, (Greek, "dokeo" = "to seem"). This error developed out of the dualistic philosophy which viewed matter as inherently evil, that God could not be associated with matter, and that God, being perfect and infinite, could not suffer. Therefore, God as the word, could not have become flesh per John 1:1,14, "In the beginning was the Word, and the Word was with God, and the Word was God...And the Word became flesh, and dwelt among us.. " This denial of a true incarnation meant that Jesus did not truly suffer on the cross and that He did not rise from the dead. By Matt Slick.
This heresy may not actually be alive and well but sadly, it still rears its ugly head on occasion.