Since I didn't quite finish my sermon, here are a couple of thoughts that remain in my mind from this great passage:
What is interesting to note is that not only does the NT picture Christ as the lamb sacrificed, but also as the priest who offers Himself as that sacrifice (Heb. 9:10ff). It is a reminder that Scripture uses as many different pictures as possible for us to understand the depth of Christ’s work. There is no one image that is adequate for portraying the infinite wonder of Christ's atoning work (in fact, Eph. 2:7 suggests that it will be our eternal preoccupation and that the Lord will eternally unfold the riches of His grace extended through the cross).
Not only is Jesus Christ the Lamb of God, but He is the eternal Lamb. Revelation 13:8 tells us that there are names that have been written in the Lamb's book of life from the foundation of the earth. That is, already in the eternal past, God had ordained the coming of Christ and the sacrifice of Christ and the salvation of those who would trust in Christ — the Lamb of God. The sacrifice of Christ was not an afterthought on God's part, nor was it a secondary plan after the intrusion of sin "messed up" His plan. That Christ would be the sacrificed Lamb has always been God's eternal plan and purpose. John Piper said it this way:
…before the world was created there was a book called the “book of life of the Lamb who was slain.” The Lamb is Jesus Christ crucified. The book is the book of Jesus Christ crucified. Therefore, before God made the world he had in view Jesus Christ slain, and he had in view a people purchased by his blood written in the book. Therefore, the suffering of Jesus was not an afterthought, as though the work of creation did not go the way God planned. Before the foundation of the world God had a book called “the book of life of the Lamb who was slain.” The slaying of the Lamb was in view before the work of creation began.
And one final implication of Christ's sacrifice: If I am in conflict with another believer, or if I do not "like" (or love!) another believer, or if I am harboring unkind thoughts and judgmental attitudes toward another believer, I must recognize that the person I dislike is the person that was loved by the Triune Godhead in eternity past to the point that Christ joyfully and willingly endured the sacrifice on the cross to redeem and save that person for His glory! So on what basis might I say that it is acceptable to be purposefully out of fellowship with such a person. Yes, that person may think and act very differently than me, may have different priorities and desires than me, and may even be difficult to engage in conversation, but that is the very person that is the object of God's eternal and divine affections. How can I remain out of fellowship with Him and in fellowship with Christ?