The sermon centres on the deadly nature of unbelief, illustrated through the tragic story of a nobleman in 2 Kings 7 who refused to trust God's promise of deliverance during a famine, resulting in his death despite witnessing the fulfillment. It traces unbelief to its origin in Genesis 3, where Satan's deception of Eve introduced doubt in God's Word, establishing unbelief as the root of all sin and a work of the devil who seeks to steal, kill, and destroy faith. The message warns that unbelief is not merely intellectual skepticism but a prideful, self-reliant rejection of God's authority, leading to mockery, moral decay, and spiritual blindness, with dire consequences including divine judgment and eternal separation from God. Drawing from Scripture, it emphasizes that unbelief is a departure from the living God, a condition that corrupts the heart and leads to destruction, yet calls listeners to repent and trust Christ today, offering salvation and eternal rest through faith in His finished work on the cross.