The sermon contrasts two opposing heart conditions: one hardened and self-sufficient, described as 'fat as grease'—symbolizing spiritual dullness, pride, and resistance to correction—and another that is soft, teachable, and deeply joyful in God's Word. Drawing from Psalm 119:70, it emphasizes that the unregenerate heart is calloused, unyielding, and unpleasing to God, much like spoiled or unclean fat unfit for sacrifice, while the believer's heart is characterized by delight in God's love and law. This delight is not passive but active, rooted in Scripture, prayer, and humility, enabling spiritual sensitivity and openness to divine guidance. The message calls listeners to examine their hearts, repent of worldly distractions, and rekindle their joy in God through regular engagement with His Word and intimate communion in prayer, ultimately cultivating a life that is both teachable and transformed.