Why as Christians do we pray out loud when we know that Satan can hear what our prayers are when we pray out loud and not silently?
Let me direct you to two places in the Bible where people prayed out loud. The first passage is Luke 11:1-2. One day Jesus was praying in a certain place. When he finished, one of his disciples said to him, “Lord, teach us to pray, just as John taught his disciples.” 2 He said to them, “When you pray, say: ‘Father, hallowed be your name, your kingdom come.’”
Here we see that Jesus Himself prayed out loud and encouraged His followers to do the same. Jesus tells them, “When you pray, say…” Since Jesus is our example in all things, we seek to do as He did.
Another passage that I want to call your attention to is Acts 4:23-24. On their release, Peter and John went back to their own people and reported all that the chief priests and elders had said to them. 24 When they heard this, they raised their voices together in prayer to God. “Sovereign Lord,” they said, “you made the heaven and the earth and the sea, and everything in them.” From these verses we see that the early disciples prayed out loud together.
My conclusion is this: since Jesus and the early disciples prayed out loud, they must not have cared whether Satan could hear their prayers or not. On a personal note, I have been encouraged again and again by the spoken prayers of others. To be with others when they are speaking to God is a marvelous thing, a strengthening thing. Silent prayer is good, but there is a place for spoken prayer, too.
— Pastor Chris