Acts 4:29-31 NIV
Now, Lord, consider their threats and enable your servants to speak your word with great boldness.  Stretch out your hand to heal and perform signs and wonders through the name of your holy servant Jesus.”  After they prayed, the place where they were meeting was shaken. And they were all filled with the Holy Spirit and spoke the word of God boldly.
As well as getting their courage from their big vision of God, these early disciples sought courage through prayer, asking that God would help them to speak and back up their words with his action. God clearly lives this prayer and respond dramatically!
Father, help us by your Spirit to speak like these disciples to our contemporaries and in your mercy back up our words through your presence.