“Paul, an apostle – sent not from men nor by man, but by Jesus Christ and God the Father”. 

Gal 1:1 NIV 

Most national leaders need to contact other national leaders somewhere along the line. Usually they select a very senior person who makes contact with another such person in the other country who then conveys the message to the other national leader. 
When the apostles of Jesus went out from Jerusalem and the surrounding area to tell people in neighbouring countries about Jesus they went under the command of God. Paul was the leading emissary in this outreach and it was decided that he would concentrate on taking the gospel to Gentiles. There were many Gentiles who had adopted Judaism – the faith of the Old Testament – in the Roman Empire. But not all Jews were happy to have this apostle of another faith come and try to convert these new recruits away from the Jewish faith. Paul was therefore often on the defensive about who he was and why he had come. Again and again he had to hammer it home to people in the churches to whom he ministered that God had sent him on his mission. He did not sit down one day and think it would be a nice trip round the countryside. God alone had implanted within him the drive to go to people who did not know of Jesus to tell them about him. 
That is still the basis when any person goes with the same message. Anyone who goes not having been sent by God will soon come a cropper. And those who receive such a person will quickly see through the “false prophet”, however cleverly disguised he or she may be. 

Lord, thank you for sending your messengers with the gospel.