This sharing time was common following the presentation of God's Word in the synagogues. Paul and Barnabas utilized this opportunity to teach "men of Israel" the Word of God regarding the Lord Jesus Christ.
God promised Israel a savior and salvation is available according to God's plan. Paul focused his sharing on God. To get born again and receive salvation a person must confess with their mouth the Lord Jesus and believe in their heart that God raised him from the dead (Romans 10:9-10). Paul began with God's choosing of His people and took his audience from God's promise to its fulfillment in His resurrection of the Lord Jesus Christ.
Acts 13:17
The God of this people of Israel chose our fathers, and exalted the people when they dwelt as strangers in the land of Egypt, and with an high arm brought he [GOD] them out of it.
God chose, God exalted, God brought them out.
Acts 13:18-22
And about the time of forty years suffered he [GOD] their manners in the wilderness. . .he [God] destroyed seven nations . . . he [God] divided the land . . .he [GOD] gave them judges . . . God gave them Saul as king . . . he [God] removed Saul from the kingship . . . he [God] raised up David . . . he [God] called David a man after His own heart . . . and
Acts 13:23
Of this man's seed hath God according to his promise raised unto Israel a Saviour, Jesus:
God's plan was for a savior from the seed of David. Jesus Christ is that man. Paul quickly brings his sharing to God's fulfillment of his promise in Jesus Christ. The first thing the audience must know to get saved is that Jesus is Lord - the promised Christ.
Next, Paul reminds them of the teaching of John and lets them know that salvation is available NOW!
Acts 13:26
Men and brethren, children of the stock of Abraham, and whosoever among you feareth God, to you is the word of this salvation sent.
Salvation is available now. Jesus was the promised Christ. The audience is on the edge of their seat. What do they need to know to get saved???
Acts 13:28-30
And though they found no cause of death in him, yet desired they Pilate that he should be slain.
And when they had fulfilled all that was written of him, they took him down from the tree, and laid him in a sepulchre.
But God raised him from the dead:
THAT'S IT! - Confess the Lord Jesus and believe that God raised him from the dead!
Acts 13:42
And when the Jews were gone out of the synagogue, the Gentiles besought that these words might be preached to them the next sabbath.
Some of the Jews and religious proselytes followed Paul and Barnabas out of the synagogue to hear more. The Word of God spoken by Paul spread like wild fire. By the time the next sabbath rolled around the whole city turned out to hear.
Acts 13:44
And the next sabbath day came almost the whole city together to hear the word of God..
It seemed the whole city was blessed by the Word of God Paul and Barnabas were sharing. However, some of the Jews saw the multitudes following Paul and Barnabas and they were not blessed.
Acts 13:45-46
But when the Jews saw the multitudes, they were filled with envy, and spake against those things which were spoken by Paul, contradicting and blaspheming.
Then Paul and Barnabas waxed bold, and said, It was necessary that the word of God should first have been spoken to you: but seeing ye put it from you, and judge yourselves unworthy of everlasting life, lo, we turn to the Gentiles.
As God's chosen people the children of Israel were approached first by Paul and Barnabas with an opportunity to believe in the Lord Jesus Christ. But God's Word of salvation is for all people. Once rejected by Israel, Paul turned to the Gentiles and spoke God's Word to them. The response to Paul and Barnabas was mixed. Some believed and got saved! Some raised persecution and had Paul and Barnabas thrown out of the city.
Acts 13:48-50
And when the Gentiles heard this, they were glad, and glorified the word of the Lord: and as many as were ordained to eternal life believed.
And the word of the Lord was published throughout all the region.
But the Jews stirred up the devout and honourable women, and the chief men of the city, and raised persecution against Paul and Barnabas, and expelled them out of their coasts.
Acts 13:51-52
But they shook off the dust of their feet against them, and came unto Iconium.
And the disciples were filled with joy, and with the Holy Ghost.
"Shaking the dust from your feet" is a Bible Lands saying which means to shake off the animosity and bitter feelings which arose between another and you as you leave, so that you may go on your way with your heart full of peace and joy, as a believer should.
Gladly
Acts