In some ways this is the climax of Deuteronomy. More than just a collection of laws and legal precepts, Deuteronomy is a covenant document that demands the wholehearted commitment of God's people. That demand is voiced here. Its simple structure lifts up the two choices being offered, as well as the consequences each choice will produce:
A The choice between life and death (v. 15)
B Obedience means life (v. 16)
B′ Disobedience means death (vv. 17-18)
A′ The choice between life and death (vv. 19-20)
Luther, and others following in his wake, have often had difficulty with this aspect of Deuteronomy. But it must be stated that Israel is not being asked to accept the covenant or become a covenant partner. In the narrative Israel had already become a covenant partner at Mt. Horeb. The relationship itself is even longer established, going back at least as far as the exodus. Moses urges obedience here, not acceptance, because obedience leads to life and prosperity, while disobedience leads to death. In verse 15, "life" is equated with "the good" (hatob) and "death" with "the bad" (hara). By couching the sermon in the second person singular ("you"), each individual Israelite is confronted with the seemingly rhetorical question, for who would not "choose life"?
15 See, I have set before you today life and prosperity, death and adversity. 16If you obey the commandments of the Lord your God* that I am commanding you today, by loving the Lord your God, walking in his ways, and observing his commandments, decrees, and ordinances, then you shall live and become numerous, and the Lord your God will bless you in the land that you are entering to possess. 17But if your heart turns away and you do not hear, but are led astray to bow down to other gods and serve them, 18I declare to you today that you shall perish; you shall not live long in the land that you are crossing the Jordan to enter and possess. 19I call heaven and earth to witness against you today that I have set before you life and death, blessings and curses. Choose life so that you and your descendants may live, 20loving the Lord your God, obeying him, and holding fast to him; for that means life to you and length of days, so that you may live in the land that the Lord swore to give to your ancestors, to Abraham, to Isaac, and to Jacob.
New Revised Standard Version Bible: Anglicized Edition, copyright © 1989, 1995 National Council of the Churches of Christ in the United States of America. Used by permission. All rights reserved worldwide. http://nrsvbibles.org