"He reasoned with them from the Scriptures."—Acts 17:2.
The account tells us that while in Thessalonica, Paul preached in the synagogue for three Sabbaths. Does this mean that his visit to the city lasted just three weeks? Not necessarily.
We do not know how soon after his arrival Paul first went to the synagogue. Further, Paul’s letters disclose that while in Thessalonica, he and his companions worked to support themselves. (1 Thess. 2:9; 2 Thess. 3:7, 8)
Also, during his stay, Paul twice received provisions from the brothers in Philippi. (Phil. 4:16) So his stay in Thessalonica was likely somewhat longer than three weeks.
Having mustered up boldness to preach, Paul spoke to those assembled in the synagogue. According to his custom, “he reasoned with them from the Scriptures, explaining and proving by references that it was necessary for the Christ to suffer and to rise from the dead, and saying: ‘This is the Christ, this Jesus whom I am publishing to you.’” (Acts 17:2, 3)
Note that Paul did not seek to stir up the emotions of his listeners; he appealed to their minds. He knew that those who attended the synagogue were familiar with and respected the Scriptures.
What they lacked was understanding. Paul therefore reasoned, explained, and proved from the Scriptures that Jesus of Nazareth was the promised Messiah, or Christ.
Francis Devasia reacted to Bible Speaks in He Mustered Up Boldness And Reasoned About The Scriptures