John Gill preaches on the profound truth that for believers, life is centered around Christ and death is a gain, emphasizing that both living and dying serve to glorify Christ. He reflects on the life of Reverend Joseph Stennett, illustrating how his ministry was dedicated to Christ and how his death is a gain, not only for him but also for the glory of God. Gill explains that in life, Christ is everything to the believer, providing wisdom, righteousness, and redemption, while in death, believers are freed from sin and enter into eternal communion with Christ. The sermon encourages the congregation to find hope in the promise of eternal life and the joy of being with Christ after death.