In Acts 12, we find the early church facing a pretty bleak scenario. They were in a situation where, if God did not come through, it would be a complete disaster. We don't like situations like that, because we like to have a backup plan. Then we like to have a backup plan for the backup plan. Then we have a backup plan for the backup plan for the backup plan.
But sometimes God will allow us to be in a set of circumstances in which there are no backup plans. There is no safety net. There is no way out but Him.
The early church was in such a situation. After a period of relative quiet, a new wave of persecution was coming against the church. Herod Agrippa I arrested James, the brother of John, one of the "sons of thunder," and then executed him. Next, he arrested Peter, a leader of the early church, and it looked as though he would be executed as well.
Herod wanted to make sure that Peter didn't get out of prison, because the last time he was thrown in jail, an angel had sprung him (see Acts 5:17–20). Herod took no chances, assigning four squads of soldiers to guard Peter. He was chained to two soldiers and guarded by 14 more.
So what did the church do? We read that "constant prayer was offered to God for him [Peter] by the church" (see Acts 12:5). We have a secret weapon in the church. It is called prayer. Though all other doors may remain closed, one door is always open—the door into the presence of God through prayer. The problem is that prayer is so often the last resort. It is what we do when all else fails. But these believers prayed.