Jesus' teaching on prayer is more complex than it appears

Jesus' statement about moving mountains with faith is not a guarantee that all prayers will be answered according to our desires. He made this statement in response to the disciples' question on failure to exercise a demon. If even the apostles could have inadequate faith, then we may also face similar struggles. The power behind miracles is God, not the size of our faith. Therefore, the size of the miracle is determined by God's will, not the extent of our belief. Hence, not all prayers will be answered as we desire, as it depends on God's will.