I know it’s old (1957), but I still enjoy reading a good F. F. Bruce commentary. Even where the scholarship’s eclipsed by recent advances, wisdom rings through. Here’s his note on Colossians 2:2 (Epistles to the Ephesians and Colossians):

As against all those who tried to intellectualize the Christian faith, speaking of knowledge (gnosis) as if it were an end in itself, Paul emphasizes that the revelation of God cannot be properly known apart from the cultivation of brotherly love within the Christian community.