We have here some of the most revealing words written about God's plan for the ages. Peter masterfully sums up what God was doing through the prophets and prophecies, and who the prophets were serving in their ministry.
Peter begins v. 10 with "concerning this salvation" - the salvation he has been explaining in the opening 9 verses. This is the salvation about the wonderful mercy of God, the resurrection of Christ, the living hope that we have as believers because we believe in a living Savior, and even the various trials we need to persevere in so that we may have a faith more precious than gold. Peter informs us that it is this salvation that the prophets had prophesied about so long ago. He does not name any one prophet but lumps them all together, as if to say "Remember all those prophets? Well every one of them were being informed in bits and pieces of the glorious grace that was to come through Someone." Though they did not name Christ as such they knew he was coming, they knew he would suffer and die for our sins, would rise again, and would fulfill many other specific prophecies as well.
Verse 11 tells us that the prophets eagerly inquired (of the Lord, I would imagine) what person this would be and when these things would take place. What anticipation they must have had! O to be one of those fortunate and faithful men, who even though many suffered and died in the service of the Lord were able to get a foretaste of things to come. Here the Holy Spirit is called the Spirit of Christ, which is a wonderful reminder that the Holy Spirit is not some rogue part of the Trinity swooping down at Pentecost in Acts 2 and taking over. He is part of the eternal Triune Godhead, involved in every part of the creation and new creation process. He does not operate on his own, but points us to Christ and is thus the very Spirit of Christ. He is the one who witnessed to the prophets, who inspired every word in the entire Book.
Verse 12 is a verse that everyone needs to memorize... and if not memorize word for word, at least become intimately familiar with the key ideas. The prophets were told that they, who lived thousands of years ago, were not serving themselves but US! Now of course, Peter is writing to a group of people here. However he is writing to a scattered and general group of people, and this is most certainly still true today. The "you" in the text is not so much specific people, but A Specific People, if you will, the people of God. The prophets were aware that they were involved in something much greater than themselves, something that would not come to pass in their lifetime even, and yet they gladly pressed in to the Holy Spirit and shared what they received from Him. So, how did they serve us? They served us by foretelling what would come to pass in Christ, namely the "things that have now been announced to you through those who preached the good news to you by the Holy Spirit sent from heaven." We see here that the news continues to spread through word of mouth, through preaching.
Preaching is under suspicion in many circles today, and partially for good reason. Many preachers have abused their positions of authority, manipulated and maligned the word of God, and had self-serving goals in the pulpit. However, the perversion of some preachers does not mean that the concept of preaching is to blame! Preaching is simply proclaiming the good news of Jesus Christ, the news that He is the Savior of the world, the One who came from Heaven, died for our sins, rose for our new life, and the One who will return to judge the living and the dead. Preaching happens when we instruct, from God's Word, others to follow Jesus Christ - his example, his teachings, his heart. Preaching is still a primary tool God uses to bring people to a saving knowledge of him. Many preachers do not preach in the biblical sense, but have made it a time for counseling sessions, nice anecdotes and self-exaltation. They will be judged harshly for this, but let us not think God does not still use preaching in mighty ways today.
Finally, this news, this GOOD NEWS about Jesus Christ which the prophets of old had some knowledge of and we now have a fuller picture of on this side of the cross, this is something into which "angels long to look". This blows my mind! Angelic creatures who serve God faithfully, who worship him constantly, are floored at the concept of God rescuing sinners. Think about it though: there are many fallen angels which we call demons, who denied God's authority and sought their own. They have been judged by God already and will be finally judged forever with Satan on the last day. However, us humans, who also deny God's authority and even his very existence (which, James tells us, even demons don't do!), God has pursued, died for, and saved?!?! This is truly magnificent, altogether mysterious and head-scratching to angels looking into it. The Gospel of Jesus Christ needs to be dwelt upon more frequently, more deeply, and it needs to cause us to be in awe of God, as the angels are. We so frequently and so foolishly believe we have it all down, and perhaps this is in part because we have so simplified it that it fits onto small brochures we can pass out to people. But angels are still longing to look into the Gospel, still awe-struck at the God of the universe for doing this. We too need hearts full of wonder at God's merciful dealings with us.