The Gnostic Gospels were written too late (2nd & 3rd centuries) to have any credible insight on actual events or foundational Christian doctrine. Gnostic teaching was identified and rejected by the Apostle John. Some of the gnostic gospels bear a familiar name as if they were written by them, but they were written well after the death of all these characters, such as the Gospel of Thomas, The Gospel of Mary, The Secret Book of James, and now the Gospel of Judas. 

Gnostics believed that all material things are evil, that Jesus was therefore not God, since He had a body, and that the world was not created by God, but by a series of lesser powers, intent on keeping the soul trapped in an evil, physical body. To them, the way to the true God was through "secret knowledge" (gnosis means knowledge).

That is why 1 John begins the way it does; 

"What was from the beginning, what we have heard, what we have seen with our eyes, what we have looked at and touched with our hands, concerning the Word of Life —  and the life was manifested, and we have seen and testify and proclaim to you the eternal life, which was with the Father and was manifested to us" (1 John 1:1-2) 

John was making it very clear that Jesus was the Word and He was a real, physical person. There really is no reason to read any of the gnostic writings unless you're curious about what kind of error was being taught at those times.