“What is missions?” seems a simple question to answer. But it is not. Because so many are now using missions with a variety of emphases — the social gospel as missions, social justice as missions, outreach as missions, and missional ministry — we want to articulate what we mean by missions.
When we use the word “missions,” we are thinking of two aspects of the missionary endeavor. First of all, missions is gospel-focused. The primary task of the church is to take the gospel to the unbelieving (Lk. 24:46-49; Acts 1:8). And the missionary’s fundamental task is to be a witness/testimony to the truth of Christ and the provision of forgiveness through Him. This is what the first church did (Acts 5:32; 8:35; 9:20-22; 10:38-43; 11:18).
Simply said, the missionary is someone who is sent with the message of Christ and His forgiveness and freedom. Missions is evangelizing the nations. Consider the great commission statements: Matthew’s gospel (Mt. 28:18-20) emphasizes that Jesus’ command was to make disciples and teach the converted to obey Christ; and Luke records (Lk. 24:46-49) that the responsibility is to testify to the work of Christ on the cross to provide forgiveness for those who repent; and at His ascension (Acts 1:8), Jesus again emphasizes the responsibility to testify to His person and work.
And the primary task of missions is further to take the gospel to the unbelieving nations, as all three Great commissions passages in Matthew, Luke, and Acts affirm. Disciples are to be made of all the nations (Mt. 28:18-20) and repentance and forgiveness is to be proclaimed to all the nations (Lk. 24:46-49), and the testimony is to go to the remotest part of the earth (Acts 1:8).
And this pattern was also evident in all Paul’s missionary journeys. In all three of Paul’s journeys, the preaching of the Word and the gospel was central. Mission expansion was about the proclamation of the gospel and the development of the biblical church in those places. This is even true of Paul’s imprisonment in Rome (Acts 28:23, 28-31).
So as we think about missions, we are thinking particularly about the spread of the gospel to the nations. And by that statement, we are also intentionally excluding things like social justice from missions. Social causes might be compassionate and the legitimate work of individual believers, but they are not the task of the church (as an entity) and they are not missions. Missions is always about the gospel and the development and growth of churches.
Secondly, missions is cross-cultural. The word “missions” does not appear in the New Testament but is derived from the Latin word mitto, meaning “I send.” And as we have considered how missions began in the NT, we have come to see that “going” is inherent in missions (Mt. 28:18-20; Acts 1:8). Missions is not what we do when we stay; missions is what we do when we go. While we do ministry locally — that is distinct from missions. Ministry to the body of Christ is what we do inside the church and evangelism is what we do outside the church and missions is evangelistic and church-building work we do outside the borders of our culture.
And further, the sending and going of missionaries has always been under the authority of the local church. We agree with the writer who said, “a missionary is not one who has gone out, but one who has been sent out.” In other words, the church has identified, equipped, charged, and sent the missionary to his task. He does not operate alone, but under the authority of the local church.
The sending of qualified men to do the work of the ministry in cross-cultural settings dominates the early church history, as recorded in Acts. Consider again the three missionary journeys of Paul. On his first journey, the Spirit and church sent the men on their missionary task (Acts 13:1-3). And that is repeated on the second journey (Acts 15:22, 33). And notice that the men were sent by the church only after the church had identified them as being equipped and able for the task. And on the third journey, Paul notes his desire to go to Achaia, but he only left after the church confirmed his desire, wrote a letter on his behalf, and then sent him on his way (Acts 18:27).
So missions is both related to and different from evangelism. It is related to evangelism in that both are attempts to proclaim the gospel to unbelievers. It is different from evangelism in that it is conducted in cross-cultural settings (generally, foreign countries, though occasionally different cultural settings within one’s home country).
In summary, every missionary endeavor involves no less than two aspects: 1) someone is sent (to another place) by the church; and, 2) the one sent is given a specific task with the gospel.
 See the records of his First journey (Acts 13:5, 32-39ff, 46-47), his second journey (Acts 15:35; 16:4; 17:22-30), and his third journey (Acts 18:28; 19:1-5, 8, 20; 20:25, 27).
 Peters, “Let the Missionary be a Missionary” Bibliotheca Sacra, October, 1965, 346. In another place, he succinctly summarizes, “There are at least three essential qualities of a missionary: (1) he is a believer sent forth—a messenger, a herald ; (2) he is sent forth with a message—he is a message bearer; (3) he is sent forth on a specific mission—he has a definite assignment and a specific purpose.” 
 See also Acts 16:4, on the same journey.