C.H. Spurgeon emphasizes the honor and responsibility of being a mouthpiece for God, as exemplified by the prophet Jeremiah. Despite facing hatred and rejection for speaking the truth, Jeremiah remained faithful, and in return, God promised to speak through him. Spurgeon encourages preachers and believers alike to desire this divine privilege, as it allows them to share pure truth with power, bringing life and hope to others. He highlights the transformative impact of God's word, which can awaken the spiritually dead and bless those who receive it. The sermon concludes with a call to pray for all servants of the Lord to fulfill this calling.