Why is Saint Paul considered gnostic? (by some)

I read that these verses (over other texts that are clearly gnostic but not attributed as such) are considered gnostic: ST. PAUL TO THE EPHESIANS - Third letter > For our wrestling is not against flesh and blood; but against > principalities and power, against the rulers of the world of this > darkness > ST. PAUL TO THE CORINTHIANS (2, 6 - 8) > Yet we do speak wisdom among those who are mature; a wisdom, however, > not of this age nor of the rulers of this age, who are passing away; > but we speak God's wisdom in a mystery, the hidden wisdom which God > predestined before the ages to our glory; the wisdom which none of > the rulers of this age has understood; for if they had understood it > they would not have crucified the Lord of glory; My question: Why is Saint Paul considered gnostic? --- Consider these various examples of people forwarding or confronting the idea: * The Gnostic Paul - Book by Elaine Pagels * Was the Apostle Paul a Gnostic? * The Gnostic Paul - Random Blog post * Paul the Gnostic Opponent of Peter Not an Apostle of Historic Christianity (PDF)