The difference between believers and unbelievers as to knowledge is not so much in the matter of their knowledge as in the manner of knowing. Unbelievers, some of them, may know more and be able to say more of God, his perfections, and his will, than many believers; but they know nothing as they ought, nothing in a right manner, nothing spiritually and savingly, nothing with a holy, heavenly light. The excellency of a believer is, not that he has a large apprehension of things, but that what he does apprehend, which perhaps may be very little, he sees it in the light of the Spirit of God, in a saving, soul-transforming light; and this is that which gives us communion with God, and not prying thoughts or curious-raised notions.
John Owen, Of the Mortification of Sin in Believers in Kapic & Taylor (eds.), Overcoming Sin & Temptation (Crossway, 2006), p117