Why does the church exist?
Under the discipline of the Holy Spirit the church exists for the maintenance of worship, the edification of believers, and the redemption of the world.
Catechism for the Global Methodist Church, question 30
27Now you are the body of Christ and individually members of it. 28And God has appointed in the assembly first apostles, second prophets, third teachers, then miracles, then gifts of healings, helps, administrations, various kinds of tongues.
12So also you, since you are zealots for spirits, seek to excel for the building of the assembly.
1Brothers, if a human is also overtaken in any trespass, you who are spiritual should restore such a person in a spirit of gentleness, watching yourself so that you also may not be tempted. 2Bear one another's burdens, and in this way you will fulfill the law of Christ. 6Let the one who is taught the word share all good things with the one who teaches. 7Do not be deceived; God is not mocked. For whatever one sows, that he will also reap. 8Because the one who sows to his own flesh will from the flesh reap corruption, but the one who sows to the spirit will from the spirit reap eternal life. 9And let us not grow weary of doing good, for in due time we will reap, if we do not give up. 10So then, as we have opportunity, let us do good to everyone, and especially to those who are of the household of faith.
11And he himself gave some as apostles, some as prophets, some as evangelists, and some as shepherds and teachers. 12For the equipping of the saints for the work of ministry, for the building up of the body of Christ. 13Until we all attain to the unity of the faith and of the knowledge of the Son of God, to mature manhood, to the measure of the stature of the fullness of Christ. 14So that we may no longer be children, tossed to and fro and carried about by every wind of doctrine, by the cunning of men, by craftiness in deceitful schemes. 15Rather, speaking the truth in love, we are to grow up in every way into him who is the head, Christ. 16From whom the whole body, joined and held together by every joint with which it is supplied, according to the working in measure of each individual part, makes the body grow so that it builds itself up in love.
12Take care, brothers, lest there be in any one of you an evil heart of unbelief in departing from the living God 13but encourage one another each day, as long as it is called 'today,' so that none of you may be hardened by the deceit of sin 14For we have become partakers of Christ, if indeed we hold the beginning of our confidence firm to the end
23Let us hold fast the confession of our hope without wavering, for he who promised is faithful. 24And let us consider how to stir up one another to love and good works, 25not neglecting to meet together, as is the habit of some, but encouraging one another, and all the more as you see the Day drawing near.

Having defined the church, the catechism asks what the church is for. The answer is the closing sentence of Article V of the Confession of Faith, quoted verbatim: "Under the discipline of the Holy Spirit the Church exists for the maintenance of worship, the edification of believers and the redemption of the world."
Under the discipline of the Holy Spirit comes first, and the scriptures assigned to this question explain why. Paul writes that "God has appointed in the assembly first apostles, second prophets, third teachers" (1 Corinthians 12:28), and that Christ himself gave "some as apostles, some as prophets, some as evangelists, and some as shepherds and teachers" for "the equipping of the saints for the work of ministry, for the building up of the body of Christ" (Ephesians 4:11-12). The Spirit orders the church's life and distributes its gifts, so that the body "makes the body grow so that it builds itself up in love" (Ephesians 4:16).
The edification of believers is the purpose these passages return to most often. Paul urges the Corinthians to "seek to excel for the building of the assembly" (1 Corinthians 14:12). Galatians gives it a practical shape: restore the one who falls "in a spirit of gentleness," and "bear one another's burdens, and in this way you will fulfill the law of Christ" (Galatians 6:1-2). Hebrews warns against "an evil heart of unbelief" and answers the danger with a command: "encourage one another each day, as long as it is called 'today,' so that none of you may be hardened by the deceit of sin" (Hebrews 3:12-13). Holding fast the confession and stirring one another "to love and good works" (Hebrews 10:24) happen in the assembly, which the writer will not let believers abandon: (Hebrews 10:25). The redemption of the world looks outward: "as we have opportunity, let us do good to everyone, and especially to those who are of the household of faith" (Galatians 6:10).
Wesley called Christian conference a means of grace, and the class meeting existed for the mutual encouragement Hebrews describes. A Methodist who attends worship, accepts the counsel of fellow believers, and gives to the church's mission takes part in all three purposes Article V of the Confession of Faith names.