Gnostics had a lot of stuff horribly wrong. For example, dualism is absurd and illogical. The concept the the flesh is evil and thus either needs to be punished or that what it does has no impact on the mind, or “spirit” as they viewed it, is a very dangerous and self destructive mindset.

They also created these elaborate genealogies of the Archons, basically their gods. Each Gnostic text has a slightly different one, but they all have one. Since it’s all about this “secret” knowledge, they actually took pride in how different they could make them. Invariably they would have Sophia (wisdom) as one of the Archons. Her child, the product of some spirit mitosis, was usually Logos (word) who came to the earth appearing to have a physical body as Jesus Christ.

Most of the Archons were good, especially Sophia and Logos. But there were a evil ones, namely Yahweh. Many Gnostics would have had no problem accepting most of what would become the New Testament, but they all rejected the Old Testament. They correctly judged the actions of Yahweh, the genocide, murder, infanticide, rape, and deceit either committed directly by or ordered by him to be evil and incongruent with the character of Jesus.

This is most likely why the Gospel of John starts the way it does:

In the beginning was the Word, and the Word was with God, and the Word was God. He was in the beginning with God. All things were made through him, and without him was not any thing made that was made. In him was life, and the life was the light of men. The light shines in the darkness, and the darkness has not overcome it. (John 1:1-5 ESV)

Not only was the Logos human, containing life, but the Logos was Yahweh. This one passage contradicted much of the core of Gnostic theology.

This is not the only evidence that John was written to counter the Gnostics. The other gospels don’t explicitly emphasize the humanity of Jesus. For all we know, the writers of those gospels, like Paul before them, may have not even thought of Jesus as a physical human being. However, humanity does seem to be at least implied or a non issue. They are more concerned with an emphasis of the divinity and royalty of Jesus. John, on the other hand, focuses on him being a very physical human being.

They weren’t the only ones in Christianity in that era who held these divergent views. The Arians viewed Jesus to be man, not God. Others viewed Jesus to be God, not man. Still others, like the Gnostics were sure that the god of the Christians and the god of the Jews could not be one in the same.

Throughout the second and third centuries there were many who did not consider the Old Testament to be scripture, a view that was most likely always a minority view, but in the end it was defeated, especially after the many counsels that were called in the third and fourth century to solidify orthodoxy and unify the church.

In many ways, it is unfortunate that the one thing that orthodoxy took from Gnosticism was the dualism, if it had been the rejection of the Old Testament, things would have been different. There would not be the likes of William Lane Craig asserting that rape and genocide are just and moral if commanded by God and nobody would reject such scientific facts as evolution.

Imagine what Christians would be like if they rejected the angry, vengeful god of the Old Testament. Odds are that they would all be humanists.