After Paul and Barnabas announced their intention to focus their evangelistic efforts upon the Gentiles in that region (due to the Jewish rejection of the message), they went on to say this - "For so the Lord has commanded us: 'I have set you as a light to the Gentiles, that you should be for salvation to the ends of the earth.' Now when the Gentiles heard this, they were glad and glorified the word of the Lord. And as many as had been appointed to eternal life believed. And the word of the Lord was being spread throughout all the region" (Acts 13:47-49).
God had planned for these men to have a special role in teaching the Gentiles the saving gospel message. Paul and Barnabas would be lights to the Gentiles, so to speak (cf. Isa. 49:6). They would help make the gospel available to all the world. This thrilled the Gentiles! Many of them praised God's word, obeyed it, and spread the gospel throughout the region.
Be careful not to interpret the unique wording of Acts 13:48 in such a way as to contradict other plain declarations of Scripture. When Luke speaks of those who had been "appointed to eternal life," certainly he does not mean that certain individuals had been unconditionally ordained for such. No, rather the New Testament speaks of God selecting beforehand a certain type of individual to be saved--that is, those with good and honest hearts who will faithfully and humbly submit to Him! Many Gentiles in that region fit that description and chose to believe, obey, and be saved (cf. Heb. 5:9). They desired eternal life and accepted it through their obedience to the gospel. Their response is not surprising since earlier they had begged to hear the word of the Lord! God has not randomly selected certain ones to be saved and certain ones to be lost. That would not be just or righteous! Even back in 13:46, we see that the wicked rejected the gospel and judged themselves unworthy of eternal life! They were responsible for their own guilt for they had free choice as to whether or not to embrace the gospel. Those who lack a heart to submit to God in obedience to His will condemn themselves and are not among the faithful who will inherit everlasting life.
"But the Jews stirred up the devout and prominent women and the chief men of the city, raised up persecution against Paul and Barnabas, and expelled them from their region. But they shook the dust from their feet against them, and came to Iconium. And the disciples were filled with joy and with the Holy Spirit" (Acts 13:50,51).
The rebellious Jews would not stand by idly while Paul and Barnabas converted souls and increased in influence. They organized persecution against them and commanded them to leave the area. Paul and Barnabas peacefully complied, in accordance with the instructions of Jesus (cf. Matt. 10:14). Although they were leaving the region to preach elsewhere, the gospel seed had been firmly planted and would continue to grow and thrive in their absence. The disciples, though they were being persecuted, were filled with both joy and God's Spirit! Clearly, we can see that joy does not depend upon external circumstances (cf. Phil. 4:4).