A man approved by God to be entrusted with the gospel

1 Thessalonians 2:1-8
Paul, they suffered and been insulted in Philippi, but with the help of our God we dared to tell you his gospel in spite of strong opposition. We speak as men approved by God to be entrusted with the gospel.
We are not trying to please men but God, who tests our hearts. God is our witness.
As apostle of Christ we could have been a burden to you , but we were gentle among us, like a mother caring for her little children.
Why?
It is clear that Paul's enemies have been engaged in a smear醜化 campaign. 
The apostle clears himself of their charges by reminding the Christians of what actually happened when he was with them. He did not come as an itinerant流動 quack嘎嘎 teacher, peddling兜售 dubious曖昧 wares and out to deceive.
He came to give, not get, willing to face more trouble while still smarting from his wounds at Philippi.
Paul preached gospel with the help of God, he did not asked anything from whom he said to, but with love and giving. Even under strong opposition, Paul dared to tell the gospel, for he knows that God is with him. The Lord said to him directly.
How?
I believed that many missionaries devote their life for gospel is because they approved by God and has been entrusted with the gospel. So I, I need to be approved by God and clearly received the signature from the Lord to show me the way.