1 Peter concludes with a benediction: Peace to all of you who are in Christ. This prayer for peace would be especially comforting for a group of Christians who were about to endure the devastating effects of Nero’s persecution of the church.
Did God ignore Peter’s prayer? Did God refuse to grant peace to these believers as the fires of persecution blazed around them? No. Not if we understand peace. Alexander Maclaren writes that "Peace comes not from the absence of trouble, but from the presence of God.” God’s people can enjoy peace amidst pain, plague, and persecution because God is present.
But how can we be sure of God’s presence? Because we are “in Christ.” This idea of being in Christ is all over the New Testament. Believers are created in Christ (Eph. 2:10), crucified with Christ (Gal. 2:20), buried with Christ (Col. 2:12), baptized in Christ and His death (Rom. 6:3), resurrected in Christ (Rom. 6:5), and seated with Christ in the heavenly places (Eph. 2:6); Christ is formed in believers (Gal. 4:19) and dwells in our hearts (Eph. 3:17); the church is the body of Christ (1 Cor. 6:15; 12:27); Christ is in us (2 Cor. 13:5) and we are in Christ (1 Cor. 1:30); the church is one flesh with Christ (Eph. 5:31–32); believers gain Christ and are found in Him (Phil. 3:8–9). In Christ we are justified (Rom. 8:1), glorified (8:30), sanctified (1 Cor. 1:2), called (1:9); made alive (Eph. 2:5), created anew (2 Cor. 5:17), adopted (Gal. 3:26), and elected (Eph. 1:4–5).
John Calvin said this doctrine is to be accorded “the highest degree of importance.” But what does it mean to be in Christ? Lord willing, sometime in the next 4-6 weeks or so my family and I will be flying to Bogota, Colombia to adopt our son and bring him home. It will not be enough to be near the airplane, on the airplane, by the airplane, over/under the airplane, or even with the airplane. We must be IN the airplane. Being in the airplane will give us the authority and the ability to travel in international airspace. Whatever happens to the plane (for good or bad) happens to me.
To be in Christ is much like being in an airplane. If God has promised to glorify Christ, then if I am in Him, in the end I will be glorified. God can no more abandon me than He can abandon His own Son.
If you have repented and believed in the Gospel, you will stand firm because you’re in Christ! As J.I. Packer says, “Your faith will not fail while God sustains it; you are not strong enough to fall away while God is resolved to hold you.”
Stand firm until the end because you’re in Christ.
 Alexander Maclaren, as quoted by https://www.preceptaustin.org/1_peter_511-14, accessed December 29, 2020.  As quoted by Marcus Peter Johnson, “10 Things You Should Know about Union with Christ,” Crossway, August 23, 2016, https://www.crossway.org/articles/10-things-you-should-know-about-union-with-christ/.  J.I. Packer, Knowing God (London: Hodder & Stoughton, 1973), 275.