Corporate worship is the collective gathering of the visible church for the sake of worshipping God through praising Him together.
Corporate Worship in the OT
Corporate worship is unique in the OT because it occurred primarily on prescribed seasons, times, and manners. The corporate worship times were called feasts and were celebrated by the nation as described in the Law - such as Leviticus 23.
Corporate worship happened only when the nation was collectively together. However, simply because corporate worship happened on designated times and seasons, it does not mean that worship of God only happened at that time. Worship, defined as an ongoing devotion to the Lord in all of life, was commanded to happen throughout life (Duet. 6:13-15).
Therefore, personal worship - devotion to the Lord in every area of life - was commanded for all of life and practiced by believers. However, in regards to corporate worship, the gathering of the nation of Israel for worship was relegated to specific times and season as stated in the Mosaic Law. Attendance at the corporate worship gatherings was mandatory and there was no sense that they were optional.
Christ makes worship accessible
Because corporate worship was assigned to particular seasons, the presence of God was limited to certain priests at certain times of the year. Although personal worship was commanded, worship in the actual presence of God was not available to just anyone. The presence of God in the Holy of Holies was strictly reserved for the High Priest in accordance with the Mosaic Law. However, all that changed at the coming of Christ.
Hebrews 10:11-14, 18-25 tells us that Christ offered of himself as a sacrifice, which has purified the worshipper for all time so that the need for a priest to offer a sacrifice on our behalf is no longer needed. Now, worshipers can go directly into the presence of God through Christ because he has made the way available to anyone. The way is called the new and living way that was made possible by Jesus' flesh - in other words by his crucifixion and resurrection.
Now, when corporate worship happens, every worshipper is allowed into the presence of God by the blood of Jesus. Unlike in the OT when only the priests were allowed, Christ makes access into God's presence available to any who would come to God by faith. Those who come to God, through the new and living way of Christ, can come in full confidence and assurance because the sacrifice he made was accepted by the Father as evidenced by the resurrection. In light of what Christ, the presence of God is accessible by any worshiper at any time, in any place.
For some Christians, the accessibility of God's presence by the individual worshiper means that church attendance and participation is completely optional since we can worship God and be in his presence at any time. But is this the right mindset? Look at the last command in Hebrews 10:25, "[Let us] not neglect to meet together, as is the habit of some..." After the author describes the new privilege of access to God's presence, he warns against neglect for corporate worship. The truth that we have access to God's presence by the crucifixion and resurrection of Christ does not mean that we no longer need to gather corporately, but it means that we should gather all the more regularly because the presence of God is more intensely experienced when we do. What does that mean? It means that individual worshippers each contribute to the corporate worship of God so that the individual members of Christ body are built up by the presence of the body of Christ corporately.
Corporate worship in the NT
When we think of corporate worship in the NT we have to begin with the truth of what it means to be made a worshiper of God. Romans 12:1 teaches that our spiritual worship is when we offer our bodies as living sacrifices to God. In addition, Hebrews 13:15 says that we should continually lift up a sacrifice of praise, that is the acknowledging of Christ's name. So, worship is the offering of our bodies and our praise. Both are sacrifices to God.
When we combine these two things we see that the individual worshipper can worship God when they offer their body to be used for God and His kingdom and when the lips are used to acknowledge Christ's name. This of course will include singing praise, but it also refers to the preaching of the gospel, the declaration of the Word of God as it is read, and the careful use of our words.
So what is corporate worship in the NT? Corporate worship is the gathering of the visible church to worship God through praising Him.
Corporate worship is characterized by: Preaching and reading scripture (1 Tim. 4:14), singing Psalms, hymns and spiritual songs (Col. 3:16; Eph. 5:19-21), praying (1 Tim. 2:1-2, 8), celebrating the ordinances of the Lords supper and Baptism (Mt. 28:19; 1 Cor. 11:17-34), and stirring up one another toward love and good deeds (Heb. 10:24-15). It seems also that a collection, or offering, is meant to be a part of the corporate worship experience (1 Cor. 16:1-3; 1 Tim. 5:17; Gal. 6:6).
The goal or purpose of corporate worship is to build one another up! Paul says that all things done in the public assembly should be for building one another up (1 Cor. 14:26). Some have thought that only the preacher builds up, but in reality, our singing can build up, our praying can build up, our reading out loud can build up, our spurring one another can build up.
John Piper talks about the building up of the church as we meet like this:
"We have the whole dynamic of collective worship, which is very significant biblically because God inhabits the praises of his people (Psalm 22:3). When people come and worship in spirit and in truth there is the presence and dynamic of the Holy Spirit that can't be repeated though a group Skype call. That will be second best, certainly. The Church, the body of Christ is to meet. We are to be with each other and we are to worship together and confess our sins and have communion and embrace people and show our love for people and weep with those who weep and laugh with those who laugh."
The Word of God in Corporate Worship
Because Christ is to be the center of all of our worship it is not strange for the Word of God to be prioritized in the gathering of the church for corporate worship.
Jesus is known primarily through the scriptures. The Holy Spirit illumines and guides, but what exactly is illuminated? Is it not the knowledge of God in the person of Christ Jesus? And what are we guided to but the person of Jesus Christ and knowledge of God? Our gatherings should be robustly biblical and exulting in God and His glorious gospel. We are to feel the weight of the truth as it is read, preached, sung, and prayed. Matt Boswell wrote in a blog, "We also want to feel deeply regarding the word of God. Theology runs its full course when doxology is its aim. God's word is meant to work through our emotions, to cause us to feel deeply, to love what we learn about God." We are taught and admonished, built up and encouraged in and through corporate worship. We gather to learn about God, be built up into Christ and to encourage one another. We assemble to praise God, knowing that God inhabits our praises. Corporate worship is the outlet by which we express our delight in God that he might be glorified by our joy.