We are shown the transition of Peter and the disciples from being behind closed doors because of fear before the day of Pentecost to having full confidence, trust, and believing on the day of Pentecost after they received holy spirit. When they listened, followed and obeyed, their fear left. When we have no fear, we are able to manifest power, and it is the manifestations in operation that will bring people to fellowship. We are instructed to believe God, to please God, and help others believe God by seeing our example of believing.