Intellectual Lethargy

"Intellectual lethargy is undoubtedly the greatest sin of many Christians today. They never grow in knowledge, they end where they began. They are always talking about first experiences, but they never entered into the riches to which Paul refers; they have never climbed the mountain tops and breathed the pure air of God's holy truth. They are content with the ordinary level; they are ignorant of the more advanced teaching because it demands an intellectual effort."

-D. Martyn Lloyd-Jones
-The Unsearchable Riches of Christ