Deuteronomy 9 · a question people ask
If the land wasn't given for Israel's righteousness, why does Moses keep tying it to obeying?
Deuteronomy says both. This chapter says three times that the land isn't given "for your righteousness" (9:4-6). Yet Moses also says, "You shall observe to do all the commandments which I command you today, that you may live, and multiply, and go in and possess the land which the LORD swore to your fathers" (8:1), and "Therefore you shall keep the entire commandment which I command you today, that you may be strong, and go in and possess the land" (11:8). Both readings below keep what 9:4-6 says, that the reasons given are the wickedness of the nations and the LORD's oath (9:5), and both keep the commands. They differ in how the two fit, and they are not exclusive of one another.
How Christians read it
Where Christians differ, Favor sets out the main views side by side and doesn't pick one.
The gift rests on the oath; obeying is how to live in it
Those who hold this view start from the reason the chapter gives: "that he may establish the word which the LORD swore to your fathers" (9:5). After the calf, the worst failure Moses tells, the LORD still says, "Arise, take your journey before the people; and they shall go in and possess the land which I swore to their fathers to give to them" (10:11). Obeying is for life in the land: "that it may go well with you and with your children after you, and that you may prolong your days in the land" (4:40). On this reading, obedience didn't earn the land; it was the way to live in what was given.
Deuteronomy 9:5 · Deuteronomy 10:11 · Deuteronomy 4:40
Unbelief could still keep them out
Those who hold this view start from Kadesh Barnea, which this chapter names: "you rebelled against the commandment of the LORD your God, and you didn’t believe him or listen to his voice" (9:23). That generation did not go in: "Surely not one of these men of this evil generation shall see the good land which I swore to give to your fathers" (1:35). Moses warns the next generation too: "As the nations that the LORD makes to perish before you, so you shall perish, because you wouldn’t listen to the LORD your God’s voice" (8:20). On this reading, the land was never a reward for righteousness (9:4-6), but trusting and obeying were real conditions of going in and staying.
Deuteronomy 9:23 · Deuteronomy 1:35 · Deuteronomy 8:19-20
The verses
“You shall observe to do all the commandments which I command you today, that you may live, and multiply, and go in and possess the land which the LORD swore to your fathers.”
“Therefore you shall keep the entire commandment which I command you today, that you may be strong, and go in and possess the land that you go over to possess;”