the context and Harmony of all scriptures also known as the unity of Scriptures. The gnostic gospels were not, in fact, Paul addressed the error of them. After the "Apostles" have died Gnosticism tried yet again to interject their writings again as authoritative.
They attacked(gnostic gospels) the word of God and the foundational truth for example:
- the death of Jesus and HIS literal resurrection
- false narratives of Jesus having a wife
- The deity of Christ
The church fathers in much prayer and seeking God took what was already written and a measuring rod formed in truth to know what was inspired. They Built of Jesus and the Eyewitnesses, the Prophets and the law. they rest fall short to meet the standard that GOD set up not man.