Christ’s church is a beautiful and wonderful thing. The very concept and existence of Christ’s church is hopeful and comforting. Why would I say that? How could the church’s existence give us hope and comfort? Let me explain.
The covenant of works was clearly defined from the beginning: “You may surely eat of every tree of the garden, but of the tree of the knowledge of good and evil you shall not eat, for in the day that you eat of it you shall surely die” (Gen. 2:16–17). The opposite was equally true. “If you abstain from eating fruit from the tree of the knowledge of good and evil, you shall continue to live and flourish in fellowship with Me.”
Westminster Confession 7:2 says, “The first covenant made with man was a covenant of works, in which life was promised to Adam; and in him to his descendants, on condition of perfect and personal obedience.”  Adam was the federal representative of all humanity. If Adam succeeded, he and all after him would live. If Adam failed, death for everyone. Sadly, Adam failed. He (and in him everyone after him; Rom. 5:12; 1 Cor. 15:22) broke the covenant of works thus introducing death into the world.
That could’ve been the end of the story, but God was pleased to make another covenant, a covenant of grace, which God expressed in seed form in the promise: “I will put enmity between you and the woman, and between your offspring and her offspring; he shall bruise your head, and you shall bruise his heel” (Gen. 3:15). That was gospel. God would raise up an offspring from woman, a son, and this son would crush the head of the serpent thus defeating evil, sin, and death. Hypothetically, God could’ve destroyed humanity for transgressing His law. Instead, he gave them gospel. Why? What was the purpose of the covenant of grace?
God’s eternal plan was to redeem a people from their sin and misery for Himself through His Son. This redemptive plan accomplished by God’s Son would glorify God by his gathering a people for His Father. The Father gave authority over all flesh to the Son, and the Son gave eternal life to all whom the Father had given him (Jn. 17:2). The Son’s redemptive work derived from God’s redemptive plan.
Because God is gracious, He did not leave humanity in their sin and misery. Instead, as the Westminster Shorter Catechism states:
God, having out of his mere good pleasure, from all eternity, elected some to everlasting life, did enter into a covenant of grace, to deliver them out of the estate of sin and misery, and to bring them into an estate of salvation by a Redeemer. 
Okay, make sure you hear the comfort in that. According to God’s eternal plan of redemption, God did not leave all humanity in their sin and misery. According to His eternal decree of election, God entered into a covenant of grace with His chosen people to deliver them out of their sin and misery and to grant salvation to them through Christ. In other words, God would save His church; God would gather his church out of the world, out of their sin and misery, to Himself and for Himself, to love and care for them forever.
For over a millennium, Christians have been confessing “I believe in the holy catholic church.” Part of being a true Christian is confessing the true church of Jesus Christ. Heidelberg 54 explains what confessing the church means:
I believe that the Son of God, out of the whole human race, from the beginning of the world to its end, gathers, defends, and preserves for Himself, by His Spirit and Word, in the unity of the true faith, a Church chosen to everlasting life. And I believe that I am and forever shall remain a living member of it.
With his precious blood, Jesus obtained a church for himself (Acts 20:28). Not one person; many persons. He ransomed his church from every tribe, language, people, and nation to be one in him (Rev. 5:9). And he made them a kingdom to reign on the earth (Rev. 5:10).
The gospel is not an individualistic message. The gospel is a corporate message. Of course, Christ saves individuals, but he saves them alongside of other individuals and unites them all in himself. Jesus saves people to gather a people, defend a people, and preserved a people. In John 10:16, Jesus said “there will be one flock, one shepherd.” Jesus later prayed, “All mine are yours, and yours are mine . . . keep them in your name, which you have given me, that they may be one, even as we are one” (Jn. 17:10-11). Jesus even prayed for those who would be saved through the apostolic gospel – you and me. He prayed that we would “all be one” and that we may be united to Father and Son (Jn. 17:21). Jesus prayed,
The glory that you have given me I have given to them, that they may be one even as we are one, I in them and you in me, that they may become perfectly one, so that the world may know that you sent me and loved them even as you loved me. (Jn. 17:22-23)
Similar to Heidelberg 54, the Belgic Confession states:
We believe and confess One [sic] single catholic or universal church—a holy congregation and gathering of true Christian believers, awaiting their entire salvation in Jesus Christ being washed by his blood, and sanctified and sealed by the Holy Spirit. This church has existed from the beginning of the world
and will last until the end, 
It’s not just that Jesus saved you. Jesus saved you into union with himself and his church catholic, his congregation, his gathering of all true believers into himself. This church exists from Eden to the return of Christ.
In similar fashion, the Westminster Confession 25:1 states:
The catholic or universal Church, which is invisible, consists of the whole number of the elect, who have been, are, or shall be gathered into one, under Christ its Head; and is the spouse, the body, the fullness of Him who fills everything in every way. 
Again, the church is from the beginning. Christ redeems the elect and gathers them into one under his headship. To belong to Christ is to belong to Christ’s church. This truth is life-changing. To belong to Christ and his church is a great comfort.
Why is this comforting? The power and grace of Christ are sufficient to save, gather, defend, and preserve his church and you within it. The gates of hell will not stop Jesus from being an effective Prophet, Priest, and King. Yes, our sin is serious and tragic, but Christ has and continues to overcome sin and death. The simple existence of the church confirms that God is gracious toward sinners, saves His people, defends His people, protects and preserves His people, and is entirely committed to loving and caring for His people forever. To belong to Christ’s church is an immense comfort because of the commitment Christ has to his church. All the promises of God to His church are ours in Christ.
It is a great comfort to know that we belong to Christ, and it is a great comfort to know we belong to the church of Christ. Though our sin and misery are great, God’s grace is greater as He counts us as one of His precious ones.
 The Confessions of Our Faith, Fortress Edition, ed. Rev. Brian W. Kinney (Fortress Book Service & Publishers, 2007), 13.
 Ibid., 126.
 The Confession of Our Faith, 45.
Quotes from the Heidelberg Catechism and creeds are taken from Zacharias Ursinus & Jonathan Shirk, The Heidelberg Catechism: True Comfort for Life & Death (Manheim: Small Town Theologian, 2021), 395.
Scripture quotations are from the ESV® Bible (The Holy Bible, English Standard Version®), copyright © 2001 by Crossway, a publishing ministry of Good News Publishers. Used by permission. All rights reserved. May not copy or download more than 500 consecutive verses of the ESV Bible or more than one half of any book of the ESV Bible.