This is from Hillsong United's album "Zion". The overtone is about the scene of Peter being called by Jesus to walk on the water, and he did, but then he temporarily lost faith and started to sink. He called on Jesus to rescue him, and Jesus did. In the bigger picture, sometimes our faith in God wanes a little bit, and then we struggle. We can't do it on our own. But when we put our full trust in Him, He responds. Always.