Opened a door of faith to the Gentiles

Acts 14:19-28
Then some Jews came from Antioch and Iconium and won the crowd over. They stoned Paul and dragged him outside the city, thinking he was dead. Then they returned to Lystra, Iconium and Antioch, strengthening the disciples and encouraging them to remain true to the faith.
Paul and Barnabas appointed elders for them in each church and, with prayer and fasting, committed them to the Lord, in whom they had put their trust. ( Barnabas adrained elders; or Barnabas had elders elected.)
From Attalia they sailed back to Antioch, where they had been committed to the grace of God for the work they had now completed. On arriving there, they gathered the church together and reported all that God had done through them and how he had opened a door of faith to the Gentiles.
Driven out of Antioch, they go to Iconium, where the pattern is repeated.
Following an attempted stoning , they escape to Lystra, where the healing of a cripple leads the people to acclaim Barnabas as Zeus(Chief god of the Greeks)  and Paul as Hermes(the messenger-god), despite their protests. 
Further trouble from the Jews of Antioch takes them on to Derbe, the furthest point of this first mission, where the response is good. Returning by the same route they encourage  the new believers, appointing leaders for each church.
Why?
Even danger and Jews opposed Paul and Barnabas they were keep going on and preached God's messages. They successfully completed the mission to Gentiles.
Strengthening the disciples and encouraging them to remain true to the faith is a leader of Christian have to do.
Paul and Barnabas make a rule of church to appointed elders at each church and prayer, fasting, committed them to the Lord, in whom they had put their trust. This is the management system of church.
How?
Keep preaching gospel to Gentile and unbelievers. This is the mission to every Christian from the Lord.