Second Treatise of the Great Seth

Second Treatise of the Great Seth is an apocryphal Gnostic writing discovered in the Codex VII of the Nag Hammadi codices and dates to around the third century. The author is unknown, and the Seth referenced in the title appears nowhere in the text. Instead Seth is thought to reference the third son of Adam and Eve to whom gnosis was first revealed, according to some gnostics. The author appears to belong to a group of gnostics who maintain that Jesus Christ was not crucified on the cross. Instead the text says that Simon of Cyrene was mistaken for Jesus and crucified in his place. Jesus is described as standing by and "laughing at their ignorance."
Those who believe Jesus to have died on the cross are said to believe in "a doctrine of a dead man." All those without gnosis - including those who had what would become orthodox beliefs, as well as the figures of Adam, Abraham, Isaac, Jacob, David, Solomon, the prophets, and Moses - are all referred to as a "laughingstock." The text shows the derision which the gnostics felt towards those who did not realize their claimed truth; that the biblical text was false (in at least certain important respects) and that the God of the Jews was not the true God. 
The Treatise of the Great Seth is written from the first-person perspective of Jesus.
Some Gnostics believed Jesus was not a man but a docetistic spirit, and therefore could not die. From the translation by Roger A. Bullard and Joseph A. Gibbons:
At the beginning of the book, Jesus states:
This statement indicates that Jesus inhabited a human body that had previously belonged to someone else, which meant the body was not his own.
He also explains that the being that created the world is not the One True God. Jesus instead proclaims:
This demonstrates the gnostic view that the God of the Hebrew Bible was not the One True God, but rather an inferior being called the Demiurge, which was created by Sophia.
Jesus also makes statements claiming that Adam, Moses, and John the Baptist were all also "laughingstocks". He says:
He says these prominent figures were "laughingstocks" because they believed that the Demiurge was the One True God, and did not know the Gnostic truth.