When the congregation - Greek: when the synagogue was dissolved.
Broken up - Dismissed. It does not mean that it was broken up by violence or disorder. It was dismissed in the usual way.
Many of the Jews - Probably the majority of them rejected the message. See Acts 13:45. Still a deep impression was made on many of them.
And religious proselytes - See Acts 13:16. Compare the notes on Matthew 23:15. Greek: proselytes worshipping.
Persuaded them to continue ... - It would appear from this that they professedly received the truth and embraced the Lord Jesus. This success was remarkable, and shows the power of the gospel when it is preached faithfully to people.
In the grace of God - In his favor - in the faith, and prayer, and obedience which would be connected with his favor. The “gospel” is called the grace (favor) of God and they were exhorted to persevere in their attachment to it.