The church is given a threefold mission; upward, inward, and outward. These three things work in unison. They create a helpful cyclical motion. When we worship God as we should we want to build others up in the church, we want to evangelize, and when we build others up they grow, they evangelize, people get saved, and we praise God; and so the cycle repeats in various ways as it is supposed to. For the church to function as it should all three of these aspects of the church’s mission must be being carried out.
We are called to sing songs of praise (e.g. Ps., Eph. 5:19; Col. 3:16) but we are not to stop there. We are called to love the LORD our God with all that we are; mind, body, soul, and, strength. Everything! We are to lay our very lives upon the altar in service to the LORD (Rom. 12:1). This is the foundational thing. Upon this the other two aspects of the church’s mission is built. If this is lacking, the church will fall.
Thus, we see the huge importance of godly, sound, and worshipful preaching and singing. If the church is to worship the LORD they must know, see, and taste the wonder of the LORD. It is to this same end that songs of worship are to be sung.
It is when the church, both individually and corporately, are crying out to the LORD in worship, and having the eyes of their hearts enlightened to God’s love, that inward nurture and outward evangelism will flow as a perpetual fountain.
We see from Scripture that one of the non-negotiables is discipleship (Matt. 28:19-20). The Church must equip the saints for the work of the ministry that they may grow up every way into Christ (cf. Eph. 4:11-16). We strive for those we disciple to show the fruits of the Spirit (Gal. 5:22-23), follow the Great Commandment (Mark 12:28-31), and practice the Great Commission (Matt. 28:18-20) themselves by teaching “faithful men who will be able to teach others also” (2 Tim. 2:2). We do this for the building up of the body and the glory of God among all the nations (Rom. 1:5).
The church is a gathering of the people of God and the people of God are told to proclaim His excellencies (see 1 Peter 2:9). The main way it proclaims God’s excellencies is through the proclamation and teaching of His Word (That is how the church expands cf. Acts 6:7; 9:31; 12:24; 13:49; 16:5; 17:11-12; 19:20). The purpose being to make disciples that are wholly committed to Christ.
We see here the importance of the two other aspects of the mission of the church. It is when we taste of the LORD in worship that we want to tell people of the wonders of the LORD. We tell the good news most naturally when we are impressed with the fact that it is good news.
For a slightly more expanded discussion see: “What is the Church?”