If a missionary is defined by the task of missions, which I understand to be disciple-making (Matt 28:19), then the answer is no. A believer is first a disciple and then a missionary. Furthermore, we are to pray that the Lord of the harvest will send laborers into his harvest (Matt 9:38). The laborers are believers who answer the call to missions. Apparently Jesus recognized that there are believers who are not laboring in the harvest field so, consequently, he extended the call to Christian mission to all believers.
I find a certain parallel between baptism (Matt 28:19; Acts 2:38) and the call to Christian mission. Baptism and labor in the harvest field are evidence of one’s prior faith in Christ. Can one be a believer without water baptism? Yes, but there is a command to obey. Can one be a believer without being a disciple-maker or laborer in the harvest? Yes, but there is a call to answer.
The concept of a missionary can be traced to Acts 13:2-3. During a revival, God told the church to send out Paul and Barnabas. Elements of the call were these: God called specific individuals, the church confirmed the call, the selected ones went away to minister, and they reported back to the sending church.
This description does not fit every Christian, and to say that every believer is a missionary will only make a useful term meaningless. To call every Christian a missionary also ignores the differences in gifts, like the zealous young pastor who urges the mechanic, dentist, and farmer in his church to be blazing street evangelists.
But every believer has a part in the mission of the church. He needs to commit to a church where the people joyfully worship God, live by eternal priorities, and love and care for all members. A person who hears the message of the missionary wants to see the community that has been created by the message, and that makes every believer important to the mission.
All believers are to be witnesses to God’s grace. Because we know how God has changed our lives, we can and should be testimonies to everyone around us by both word and example.
However, not all believers/witnesses are missionaries! A missionary is one who crosses barriers with the express purpose of taking God’s message to the people on the other side. The barriers may be geographical (another place), cultural (another way of life), linguistic (another language), philosophical (another world view), or racial/ethnic. The more the barriers, the greater the effort must be in order to make the gospel understandable to those who hear it.
The Christian who testifies to his next-door neighbor or his companion at work is a witness, as we all should be. The believer who ventures into the inner city and learns the life and slang of the street, relating to the people on their level so as to share the gospel with them, is a missionary. Let’s not weaken or lessen the designation of those who make that concerted effort.
As always, the answer depends on the definition of terms. While not every believer may properly be called a “missionary” by the traditional definition (e.g. someone who is sent by The Church for the purpose of growing The Church in a new and different place among unreached or under-reached people groups,) missional living should describe the life of every true believer.
Ministry is life, and we are all called to be ministers of God’s reconciliation. Whether we eat, drink, or whatever we do, we are to do it all to the glory of God (I Cor. 10:31). Christ has given to us (anyone who is in Christ) this ministry of reconciliation (II Cor 5:17-20). As His ambassadors to a lost world and as members of the Body of Christ in a place, we are all called to use the gifts, talents, and resources we have to spread the rule and reign of Christ. In that sense, every believer is to be a minister of reconciliation whether they live in India or Indiana.
No, every believer is not a missionary. Every believer is to be a witness (Acts 1:8), but not an "ambassador" or "sent one." If every believer is a "missionary," then "missionary" becomes a meaningless word or role in regards to crossing cultures, penetrating regions to reach "unreached people-groups,” the necessity for language-learning, etc. A missionary is a "sent one" as Barnabas and Paul experienced (Acts 13:2-3). It is a special responsibility in the true sense of the word. If every Christian were declared to be a "missionary," there would be a violation of Paul's teaching regarding spiritual gifts given to believers. If every Christian were a missionary, then every Christian must also speak in tongues or interpret or heal or prophesy or – well, you get the picture – which is a violation of Scripture (see I Corinthians 12:1 ff). If we were to conclude that EVERY Christian is a preacher, then what does the role or title "preacher" mean? Let's keep it biblical ..."and ye shall be witnesses...."
The early church began with a mission. The church was initiated by the Spirit's mighty baptism and was immediately on mission with Him. While every believer within the nascent church was a witness, it was the Spirit who separated Paul and Barnabas to be missionaries. That is, God did not call every believer, but certain believers, to invade other cultures with a bold proclamation of the Gospel. Not every believer was divinely separated to the task of cross-cultural ministry. It is obvious that this holds true in the 21st century. Not every believer is a missionary as we have come to understand that term today.
However, every true believer is missional. She lives her life with one over-arching purpose, to make disciples of all nations. Christ gave that commission to the whole church, not just to a designated group of people known as “missionaries.” We make this distinction at great risk to the purpose of the Church and to the billions who have never heard the Church’s message. Is every believer a missionary? No. Is every believer missional? Yes!