God—by His calling, granting us repentance, giving us His Spirit, helping us understand the gospel of the Kingdom of God, and the revelation of Jesus Christ and His sacrifice—has brought us to a place that is spiritually identical to that of the Israelites after the Old Covenant was confirmed. Thus, this passage cries out to us with great forcefulness.
The world, and even some who claim membership in the church of God, tell us that salvation is secure once we have been justified by God's grace. They say that salvation from that point on is unconditional. If salvation is unconditional from justification on, why does God admonish us to choose between life and death? Why does He command us to choose to keep His law so that we may live and inherit the land? Why does God threaten us, His children, with the Lake of Fire (Revelation 20:15)? Are His threats hollow? Are they lies because there really is no Lake of Fire?
If salvation is unconditional after we receive God's Holy Spirit, then the death of an entire generation (except for Joshua and Caleb), lost because of faithlessness, is nothing but a misleading waste. God, then, expended over a million lives for no good reason. But I Corinthians 10:11 says, "Now all these things happened to them as examples, and they were written for our admonition, upon whom the ends of the ages have come."