Horatius Bonar emphasizes the stark contrast between the rewards for the conquerors and the doom for the cowards as depicted in Revelation 21:6-8. He highlights that those who thirst for the living water offered by Christ will inherit all things and be called sons of God, while the fearful and unbelieving will face eternal separation from God. Bonar urges listeners to recognize the urgency of accepting Christ's grace before it's too late, warning against the cowardice that leads to spiritual death. He calls for repentance and assurance of salvation, reminding that even those who have sinned can be washed clean through Christ. The sermon serves as both a warning and an invitation to embrace faith and courage in the face of worldly fears.