Question: A reader sent the following question via email: "Acts 4:4 speaks of Peter addressing an audience of 5,000 people. Professor of New Testament Robert M Grant says: 'Luke evidently regarded himself as a historian, but many questions can be raised in regard to the reliability of his history [ . . . ] His 'statistics' are impossible; Peter could not have addressed three thousand hearers without a microphone, and since the population of Jerusalem was about 25-30,000, Christians cannot have numbered five thousand (Grant, Robert M., A Historical Introduction to the New Testament (Harper and Row, 1963))."
Response: Actually, Acts 4:4 does not say that Peter was addressing an audience of 5,000 people. The 5,000 refers to the number of people who became believers, not to the number of people who might have been able to hear Peter speak at any one particular moment in time. And, it is worth noting that Acts 4:1 makes it clear that Peter was not the only speaker.
When a person, such as Grant, makes a claim that overlooks obvious and important details such as these, the rest of the claim deserves to be called into question.
Acts 3 provides details on the events that led up to Acts 4:4. In Acts 3, Peter performed a miracle, by healing a man who had never been able to walk. After the miracle, a crowd gathered before Peter and John and the two Apostles began preaching, but there is no mention of the size of the crowd. In Acts 4:1-3, Peter and John are arrested after preaching about the resurrection of Jesus. Acts 4:4 then says: "However, many of those who heard the word believed; and the number of the men came to be about five thousand" (Acts 4:4, NIV).
Reading that verse carefully shows that it isn't making a claim as to the number of people who heard or could have heard Peter, or John, at any one particular moment in time. The verse is telling us how many people had become believers.
As for Grant's estimates about Jerusalem's population, he claims that there were only 25,000 to 30,000 people living in Jerusalem at the time. Even if this were true, why must we conclude that it would be "impossible" for 5,000 people to be believers in a town with 25,000 to 30,000 residents?
As for the actual population of Jerusalem during the first century, scholars and commentators offer a variety of opinions that range from thousands to hundreds of thousands.