Final answer:
The Gnostics claimed Paul as their ultimate authority 4. because he referred to hidden 'mysteries' in his teachings, resonating with the Gnostic belief in esoteric knowledge as the path to salvation.
Step-by-step explanation:
The Gnostics claimed Paul as their ultimate authority primarily because Paul referred to "mysteries" in the gospel that were "hidden" and only available to those who were "mature," just as the Gnostics did. This aligns closely with the Gnostic belief in secret knowledge as a path to salvation. Paul's teachings, which included elements like the notion of Christ's death being a part of a divine plan and his gospel containing hidden wisdom, resonated with Gnostic thought. Additionally, his messages were at times parallel with mystery religions, which influenced the spiritual landscape of the time, and thus it allowed an affinity between Pauline thought and Gnostic interpretations.
Gnostics cherished esoteric knowledge and had a perspective of Christianity that included secretive elements, such as specific incantations and names of God believed to grant salvation and power on Earth. This esoteric approach matched well with Paul’s discussions of deeper wisdom available to the mature, creating a theological justification for the Gnostics to see Paul as a source of authority.