The sermon explores the spiritual blindness of unbelievers and the sovereign power of God to grant sight through the gospel. It emphasizes that ministry is sustained by mercy rather than human effort, requiring preachers to present an undiluted message of Christ without self-promotion. The text highlights Satan's role in blinding minds while affirming that only God can illuminate hearts with the knowledge of His glory in Jesus Christ. Believers are encouraged to trust in this divine power for evangelism, recognizing that conversion is a creative act of God similar to the light brought into existence at creation. The central call is to preach Christ alone and pray for God to shine light into the darkness of those who are perishing.