A phrase in a verse found in Acts 6 has always intrigued me. Acts 6:7 says,
And the word of God continued to increase, and the number of the disciples multiplied greatly in Jerusalem, and a great many of the priests became obedient to the faith.
Why did Luke give that detail regarding the priests? Certainly seeing Jewish priests, who often were sworn enemies to the gospel, becoming Christians testifies to the power of the gospel. Yet the context indicates that as true as this is, the Lord used a means for bringing them to faith.
This verse regarding the great increase of God's Word and new disciples follows the account in Acts 6:1-6 of the early church in Jerusalem choosing deacons to care for the widows in their midst. At that time, the widows who were culturally more traditionally Jewish (spoke Hebrew, native born to Israel, etc.) were more well-cared for than those Jewish widows influenced by the Hellenistic culture of their day (spoke Greek, born outside of Israel, etc.). Seeing this problem, the church chose seven men, themselves Hellenistic, to care for this situation.
As these deacons served in the church, caring for all the widows, the Lord blessed greatly. The apostles, freed from this responsibility, were able to pray and preach with greater effect. The people in Jerusalem, hearing the gospel and seeing the love of Christ on display in the care of the lowly, were drawn in great number to Christ. And among that great number were priests.
But why would they have especially been affected by this witness? Recall that in the Old Testament the priests were the ones responsible for mercy. They were tasked with collecting the tithes and distributing them to the widows, orphans, and strangers in their midst. However, as Jesus made abundantly clear in his ministry, at this point in Israel's history the priests were neglectful of this basic duty. Recall that the true villains in the Parable of the Good Samaritan were not the robbers who left the poor man beaten and bloodied on the side of the road, but the priest and the Levite who passed by him on the other side. The priests tithed, but "neglected the weightier matters of the law: justice and mercy and faithfulness" (Matt. 23:23).
When these priests saw a church with deacons truly caring for others, they were undoubtedly convicted of their sins of neglect. Hearing the gospel of forgiveness of sins with its call to show true love to others, they repented and believed upon the Lord that they both heard and saw in the church. Of course, one of those deacons was Stephen, who ultimately gave his life for the gospel and spread the testimony of the church even further. Such is the powerful witness deacons can have.