God's incredible love for humanity was the very impetus that would cause Him send His beloved son, Jesus, to be the sacrifice for the sins of the world. He loved us that much. We when we are in relationship with him bring him pleasure and joy. Our chief end is to love God and enjoy him in a dynamic unhindered relationship forever. The fact that God created us with the freedom to love and worship him, and then, after the choice to sin by Adam, sends His own beloved Son to this earth unambiguosly reveals God's desire to be in fellowship with his choice creation humanity.
While worship and relationship is the ultimate goal and destiny, mission is temporary. The door of worship is open and the extravagance of a relationship with God is continuously available; however, there are limits in time to the opportunity for mission. We are motivated by the fact that Jesus is the sole answer to life, family, poverty, injustice, sickness, oppression, and disease. God does use human enterprise to enforce his desires in those areas, but Jesus is the ultimate hope.
When I think about what my life could or would look like without Christ, I shudder. I am too well-acquainted with my own inadequacies, insufficiences, brokenness, sin, and ineptitude to even want to remotely imagine what my present state would--the good news is that I do not have to do that!!! God changed, restored, revived, renewed, and saved my life. The assurance of a present and future hope that comes in a dyanamic life-giving relationship with the King of Kings can not be spoken of enough! The problem is...many people still do not know this truth nor have they experienced it personally.
What motivates us? The fact that there are still billions on earth they have not experience the life-changing power of Christ in their own hearts and lives is what motivates me. I have experienced something that is otherworldly, and man, I want shout it out and let others get in on the action!