What is the reason for prosperity? There are many preachers that claim that if you are faithful to God, God will be faithful to you and prosper you here and now. There are many people who believe these preachers. There are some that believe a version of this that may not be spelled out as fully, but they understand that they have received blessings by God in their lives (job, family, home, etc.) because they have been obedient and faithful to God.
Much of the Old Testament tends to support this understanding of how the world works. Yet two passages in Deuteronomy flatly contradict this understanding. They are 8:17-18 and 9:4-5
Don’t think to yourself, My own strength and abilities have produced all this prosperity for me. Remember the Lord your God! He’s the one who gives you the strength to be prosperous in order to establish the covenant he made with your ancestors—and that’s how things stand right now.
Once the Lord your God has driven them [the Canaanite nations] out before you, don’t think to yourself, It’s because I’m righteous that the Lord brought me in to possess this land. It is instead because of these nations’ wickedness that the Lord is removing them before you. You aren’t entering and taking possession of their land because you are righteous or because your heart is especially virtuous; rather, it is because these nations are wicked—that’s why the Lord your God is removing them before you, and because he wishes to establish the promise he made to your ancestors: to Abraham, Isaac, and Jacob.
It is not because Israel was particularly faithful that God blessed them. On the contrary, Deuteronomy gives a detailed list of every time Israel was not faithful and how gracious God has been that he did not wipe them off the face of the earth. Instead, the message is that God is going to prosper them for a reason, which will fulfill part of the purposes of God.
It is actually very humbling to think that the entire reason God gave the Promised Land to Israel was not because of their faithfulness, but because he used them to judge the unrighteousness of the nations that were there. In this respect, Israel is no different than Assyria and Babylon later in the biblical narrative, since God will use those nations to judge unrighteous and unfaithful Israel.
It is also very humbling to apply this concept to our lives. If we are blessed, it may not be because of anything we ourselves did. It may be for some reason completely unrelated to us at all. The question then is not, “What did I do to deserve all that I have?” but rather, “How can I be faithful with what God has entrusted me, for whatever reason he has done it?”