So then [it is] not of him that willeth, nor of him that runneth, but of God that sheweth mercy.
Note 8 at Ro 9:16: There is a very subtle trap that many people who have been used of God fall into. They see what God has accomplished through them, and they begin reasoning, "God must use me because of my great faithfulness." But that is not the case. God has never had anyone qualified working for Him yet. God is a lot more merciful than we are faithful.