The sermon focuses on the importance of blood in saving the Israelites from the final plague in Egypt, connecting it to Jesus' ultimate sacrifice for our sins. By marking their doorposts with lamb's blood, the Israelites were spared from death, illustrating the power of blood in bringing deliverance. The sermon emphasizes that throughout history, bloodshed has been a means of atonement for sin, culminating in Jesus' sacrificial death on the cross. Believers are urged to accept Jesus' blood as payment for their sins and live in gratitude for the salvation it brings.