The events in the Gospel reading from Matthew 16:13-20 took place in the region of Caesarea Philippi. It was a territory where pagan gods were worshipped, and it is there that Jesus asks Peter a question about his identity, not in some safe territory, but in a non-believing location. Perhaps that is why Jesus told the disciples not to tell anyone that he is the Messiah, but I think the real reason is because Jesus had a special sense of timing about his ministry. He did not think it was time to reveal his true identity to the world. He was well aware that his claim was volatile in nature, and it was the claim that ultimately led to his crucifixion.