John Piper, in a sermon, “I Will Build My Church–From All Peoples” said:
In Matthew 16:15 Jesus asks his disciples, “Who do you say that I am?” Peter answers in verse 16, “You are the Christ [the Messiah], the Son of the living God.” To this Jesus says in verse 17-18, “Blessed are you, Simon Barjona, because flesh and blood did not reveal this to you, but My Father who is in heaven. I also say to you that you are Peter, and upon this rock I will build My church; and the gates of Hades will not overpower it.” In other words, “On you, my authoritative apostle, and my inspired proclaimer of the gospel, I will build my church. I will build my church on the apostolic word.”
What I want to drive home here is the triumphant authority of this promise. World missions is not ultimately dependent on human initiative or human wisdom or human perseverance. It is ultimately dependent on the power and wisdom and faithfulness of the risen and living Christ to keep this promise: “I will build my church.” Not, “You will build my church.” Or, “Missionaries will build my church.” Or, “Pastors will build my church.” But, “I will build my church.”
So Paul was jealous to give this glory to Jesus. In Romans 15:18 he says, “I will not presume to speak of anything except what Christ has accomplished through me, resulting in the obedience of the Gentiles by word and deed.” Christ accomplished it. Christ brought about the obedience of the peoples. Yes, missionaries are crucial. Pastors and elders are crucial. But we are not ultimate. Christ is ultimate. “I will build my church.” One missionary plants. Another missionary or pastor waters. Yes. But Christ gives the growth (1 Corinthians 3:6). Christ builds the church. Church planting and church establishing is supernatural work, or it is not the church that gets built, but only a human organization.
This was the point of the way Matthew ended his gospel in 28:18-19, where Jesus said, “All authority has been given to Me in heaven and on earth. Go therefore and make disciples of all the nations.” I have authority to do it – over all the powers of darkness, over death and hell, over government and terrorists – and I will do it. I will build my church. So go! I will be with you.
Knowing God through His Word ... Day by Day 
Church builder is the hand, behind it is divine power which makes things happen. Call it supernatural, miracle or faith, ultimately Church builder is only a mediator.