Why is worship essential to the life of the church?
The assembling of the people of God for worship is necessary to Christian fellowship and spiritual growth.
Catechism for the Global Methodist Church, question 32
2:41So those who received his word were baptized, and there were added that day about three thousand souls. 2:42They were continuing in the apostles' teaching and in the fellowship, in the breaking of the bread and in the prayers. 2:43Fear came upon every soul, and many wonders and signs occurred through the apostles. 2:44All who believed were together, and they held everything in common. 2:45They sold their possessions and property and distributed them to all according to each one's need. 2:46Day by day they continued together in the temple, broke bread in their homes, and partook of food with gladness and sincerity of heart. 2:47They praised God and enjoyed favor with all the people. The Lord added daily those who were being saved. 4:31After they prayed, the place where they were assembled was shaken, and they were all filled with the holy Spirit and spoke the word of God with boldness.
11For I long to see you, that I may impart to you some spiritual gift to strengthen you, 12that is, that we may be mutually encouraged by each other's faith, both yours and mine.
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.
The previous question established that worship is right for every person. This one asks about the church as a body, and the answer is again drawn from Article XIII of the Confession of Faith: "divine worship is essential to the life of the Church, and the assembling of the people of God for such worship is necessary to Christian fellowship and spiritual growth." The creed's "one holy catholic and apostolic church" is a gathered church; the word the creed uses for church means an assembly.
The scriptures for this question describe what happens when believers assemble. In Jerusalem the baptized "were continuing in the apostles' teaching and in the fellowship, in the breaking of the bread and in the prayers" (Acts 2:42). Luke adds that "day by day they continued together in the temple, broke bread in their homes, and partook of food with gladness and sincerity of heart" (Acts 2:46). Later, after the apostles prayed together, "the place where they were assembled was shaken, and they were all filled with the holy Spirit and spoke the word of God with boldness" (Acts 4:31). The Spirit came upon a congregation at prayer.
Christian fellowship and spiritual growth are the two fruits the answer names. Paul tells the Romans that he longs to see them "that we may be mutually encouraged by each other's faith, both yours and mine" (Romans 1:12); even an apostle expected to be strengthened by the faith of ordinary believers. Hebrews connects the assembly to perseverance: "Let us hold fast the confession of our hope without wavering," and "let us consider how to stir up one another to love and good works" (Hebrews 10:23-24). The writer then names the habit to avoid: (Hebrews 10:25).
Wesley held that there is no holy solitary religion; the Christian life is lived in company. The Methodist societies met weekly, and the church still expects its members to be present at worship on the Lord's Day. Article XIII of the Confession of Faith gives the reason: fellowship and growth require the people of God to be in one place, hearing the Word and praying together.