God's Call to Service (lesson -4)

God could have reached His object in saving sinners without our aid; but in order for us to develop a character like Christ's, we must share in His work. In order to enter into His joy,the joy of seeing souls redeemed by His sacrifice,we must participate in His labors for their redemption.
The Desire of Ages, p. 142.

As His representatives among men, Christ does not choose angels who have never fallen, but human beings, men of like passions with those they seek to save. Christ took upon Himself humanity, that He might reach humanity. Divinity needed humanity; for it required both the divine and the human to bring salvation to the world. Divinity needed humanity, that humanity might afford a channel of communication between God and man.
 The Desire of Ages, p. 296.