Know that the Lord is God - Psalm 100:1-3

Psalms 100:1-3 NIV

[1] Shout for joy to the Lord, all the earth. [2] Worship the Lord with gladness; come before him with joyful songs. [3] Know that the Lord is God. It is he who made us, and we are his; we are his people, the sheep of his pasture.

This is, in essence, the gospel. That the whole earth knows that Jesus is God, therefore it shouts for joy with gladness, worships Him, and comes before Him with joyful songs. The whole earth acknowledging that Jesus is Lord, and bowing before Him in worship! What an awesome image!

When Paul and some of his companions were in Thessalonica, he went into the synagogue "reasoning with them from the Scriptures, explaining and proving to them that the Messiah had to suffer and rise from the dead. 'This Jesus I am proclaiming to you is the Messiah,' he said."

Many Jews, Gentiles and prominent women were persuaded that Jesus was the Messiah and joined Paul and Silas. However, Paul's message stirred the jealousy of the Jews, and caused quite a commotion among those who were not persuaded. They rounded up some "bad characters" and formed a mob and started a riot in the city. Then they rushed to a believer's house named Jason, looking for Paul and Silas. When they did not find them there, they brought Jason and the other believers before the city officials shouting, “These men who have caused trouble all over the world have now come here, and Jason has welcomed them into his house. They are all defying Caesar’s decrees, saying that there is another king, one called Jesus.”

This last part - there is another king, one called Jesus - is the part I want to get to, but before that, if you remember when Pontius Pilate presented Jesus before the crowd he said, "Here is your king", but the Jews responded, "We have no king but Caesar. " The Jews who crucified Jesus denied that He was their king, just as many of the Jews in this incident which took place in Thessalonica with Paul did. And, just as many people in the world today do, including Jews.

The point is, Jesus is the Messiah, the Anointed King. In Jesus and Paul's day, the Jews were jealous because of Jesus, so they claimed alignment with Caesar, but Paul and the believers in Thessalonica were preaching, "there is another king, King Jesus." 

There is an alternative Kingdom that is not of this world, that King Jesus reigns over, that a lot of people are not aware of. It is our job as the ambassadors of the King to let them know. 

Acts 17:3, 7 NIV

[3] explaining and proving that the Messiah had to suffer and rise from the dead. “This Jesus I am proclaiming to you is the Messiah,” he said.

[7] and Jason has welcomed them into his house. They are all defying Caesar’s decrees, saying that there is another king, one called Jesus.”