The Bible is essential to the Lord’s mission of drawing, converting, giving new birth, and sanctifying the spiritually-lost people of this world. Of this truth, we are reminded in the Book of Concord:
Therefore, in his immeasurable goodness and mercy God provides for the public proclamation of his divine, eternal law and of the wondrous counsel of our redemption, the holy gospel of his eternal Son, our only Savior Jesus, which alone can save. By means of this proclamation he gathers an everlasting church from humankind, and he effects in human hearts true repentance and knowledge of sin and true faith in the Son of God, Jesus Christ. God wants to call human beings to eternal salvation, to draw them to himself, to convert them, to give them new birth, and to sanctify them through these means, and in no other way than through his holy Word (which people hear proclaimed or read) and through the sacraments (which they use according to his Word).
From: Solid Declaration, Article II: Free Will, in the Book of Concord, [Kolb/Wengert version], p. 553, paragraph 50.