The Church which Jesus “purchased with His own blood” (Acts 20:28) is not a building or denomination. The Church is “a holy congregation of true Christian believers, all expecting their salvation in Jesus Christ, being washed by His blood, sanctified and sealed by the Holy Spirit. This Church has been from the beginning of the world, and will be to the end thereof; which is clear from the fact that Christ is an eternal King, which without subjects He cannot be [Matthew 16:16-19].” This “holy Church is not confined, bound, or limited to a certain place or to certain persons, but is spread and dispersed over the whole world [Ephesians 4:4-6]” (BC, article 27). This one universal church of all true believers is often called the invisible church because only God can see the total number of all believers from all times and places. There are no hypocrites in the invisible church.
This does not mean the visible local church is not important. In fact, it is through the visible church that God’s elect are brought to faith in Jesus Christ and learn to become His faithful disciples (Matthew 28:18-20). True faith is “worked in man by the hearing of the Word of God and the operation of the Holy Spirit [Romans 10:17]” (BC, article 24).
There are express commands in Scripture requiring believers to unite together with other believers in the outward and public profession of their faith before the world (Hebrews 10:25). Christ has appointed that His disciples shall be solemnly received into His Church by the initiatory rite of baptism (Matthew 28:19; Acts 2:38-42); and that the central doctrine of the faith be publicly commemorated in the Lord’s Supper (1 Corinthians 11:23-26).
Christ has taught us “that there must be ministers or pastors to preach the Word of God and to administer the sacraments; also elders and deacons [Acts 6:1-6; 1 Corinthians 9:27; Ephesians 4:11-12; 1 Timothy 5:17] … that by these means the true religion may be preserved, and the true doctrine everywhere propagated, likewise transgressors chastened and restrained by spiritual means; also that the poor and distressed may be relieved and comforted, according to their necessities. By these means everything will be carried on in the Church with good order and decency [1 Corinthians 14:40], when faithful men are chosen, according to the rule prescribed [in 1 Timothy 3]” (BC, article 30)
Therefore, all believers are in duty bound to join and unite themselves with a true and faithful church, “maintaining the unity of the Church; submitting themselves to the doctrine and discipline thereof; bowing their necks under the yoke of Jesus Christ [Hebrews 13:17]; and as mutual members of the same body, serving to the edification of the brethren, according to the talents God has given them [1 Peter 4:9-10]” (BC, article 28). “The marks by which the true Church is known are these: If the pure doctrine of the gospel is preached therein; if it maintains the pure administration of the sacraments as instituted by Christ; if church discipline is exercised in punishing of sin; in short, if all things are managed according to the pure Word of God, all things contrary thereto rejected, and Jesus Christ acknowledged as the only Head of the Church” (BC, article 29).
As Christians we assemble on the Lord’s Day to worship God by praying, hearing the Word of God read and preached, singing psalms and hymns, giving offerings, and receiving the sacraments. Rather than catering to man, we seek to worship God only in the ways He mentions in the Bible. “And therefore we reject all human inventions, and all laws which man would introduce into the worship of God, thereby to bind and compel the conscience in any manner whatever. Therefore we admit only of that which tends to nourish and preserve concord and unity, and to keep all men in obedience to God” (BC, article 32).