What is "missionary work" and is that scriptural?
Does God call us to a particular occupation, such as God has "called me" to this career or that career. Is all this scripturally sound?
Missionary work has come to mean going to foreign country to teach the gospel. Sometimes it is expanded to taking the gospel to areas of your own country where the gospel hasn't been preached or hasn't been well received.
However, the origin of "missionary" is a reference to people sent on a mission. "Now in the church that was at Antioch there were certain prophets and teachers: Barnabas, Simeon who was called Niger, Lucius of Cyrene, Manaen who had been brought up with Herod the tetrarch, and Saul. As they ministered to the Lord and fasted, the Holy Spirit said, "Now separate to Me Barnabas and Saul for the work to which I have called them." Then, having fasted and prayed, and laid hands on them, they sent them away" (Acts 13:1-3). In one sense the Holy Spirit sent Paul and Barnabas to teach the gospel, but also notice that the Spirit insisted that the church do the sending. The Spirit did not choose to do it directly. Thus, we conclude that the Holy Spirit was setting a precedence for the church to send labors to the fields. The church gave these men missions to spread the Gospel. Thus, they are missionaries, even though that particular word is not used in the Bible. "And how shall they preach unless they are sent? As it is written: "How beautiful are the feet of those who preach the gospel of peace, Who bring glad tidings of good things!"" (Romans 10:15).
God has called men in the past to specific duties. For instance, Paul was told he would be taking the Gospel to the Gentiles. "But rise and stand on your feet; for I have appeared to you for this purpose, to make you a minister and a witness both of the things which you have seen and of the things which I will yet reveal to you. I will deliver you from the Jewish people, as well as from the Gentiles, to whom I now send you, to open their eyes, in order to turn them from darkness to light, and from the power of Satan to God, that they may receive forgiveness of sins and an inheritance among those who are sanctified by faith in Me" (Acts 26:16-18). Thus Paul said, "Paul, a bondservant of Jesus Christ, called to be an apostle, separated to the gospel of God" (Romans 1:1).
The mistake people make is assuming that God does this for everyone and that is not so stated in the Bible. God calls all people to be saved through His Word, but God doesn't say He assigns each person a particular task in life. See: All in a Name