Missions is not the ultimate goal of the church. Worship is. Missions exists because worship doesn’t. Worship is ultimate, not missions, because God is ultimate, not man. When this age is over, and the countless millions of the redeemed fall on their faces before the throne of God, missions will be no more. It is a temporary necessity. But worship abides forever. Worship, therefore, is the fuel and goal of missions. It’s the goal of missions because in missions we simply aim to bring the nations into the white-hot enjoyment of God’s glory…. But worship is also the fuel of missions. Passion for God in worship precedes the offer of God in preaching. You can’t commend what you don’t cherish…. Where passion for God is weak, zeal for missions will be weak….
– John Piper in Let the Nations Be Glad