What does Acts 12:16 mean?

A group of Jesus-followers had been meeting at the home of Mary, the mother of John Mark. This is possibly in the upper room where Jesus held the Last Supper. They are praying Peter would be released from prison. After arresting and beheading the apostle James, Agrippa planned the same fate for Peter. But moments before Peter's "trial," an angel appeared and rescued him (Acts 12:1–11).

Once freed of the prison, Peter made his way to Mary's house to let his friends know he was safe. Mary's servant girl, Rhoda, was so excited to see Peter she left him outside the gate and rushed to tell the prayer warriors. Instead of believing their "earnest prayer" (Acts 12:5) for Peter had worked, they assumed Rhoda was mistaken; it must be Peter's guardian angel (Acts 12:12–15).

Several times the Bible states that belief is an essential step in receiving a positive answer to prayer. Jesus told the disciples, "And whatever you ask in prayer, you will receive, if you have faith" (Matthew 21:22). This doesn't mean we can receive anything we want if only we have enough faith. We must also pray according to God's will (1 John 5:14). In this case, Peter's release is in God's plan. But the church members won't learn this until they go to the gate and look! Even when they see the evidence with their own eyes, it's still a shock.