The Reformation talks all the time about "civil righteousness," and it is patently obvious that obedience to God's Law (revealed both in nature and Scripture) brings to some degree its own rewards. There is no doubt that there are nations that are more or less just, and that there may be a correlation between prosperity and rule of law, for instance. But I believe that biblically speaking this is under the category of wisdom, or practical knowledge. So we can learn from the ant: work hard, save, and you will be well provided for during times of famine.

But that's not "divine blessing" in any sort of redemptive sense. The main problem with such a view is that it confuses the biblical categories of nature and grace. God rules the world by providence, but that isn't saving. He rules the church by his Word, and by Grace. These are two different realms, and we as Christians have "dual citizenship," we operate in both realms at the same time. But if we confuse them, we are doomed to all sorts of errors (including linking China's future growth and prosperity with the Christian faith of some of its residents... there is no divinely revealed connection between those two things, though they are both under the mysterious supervision of God.

I'd suggest you read David VanDrunen's "Living in God's Two Kingdoms." It lays out these categories for us quite clearly of traditional Reformed Two Kingdoms thought, which is my guide to how I think about politics. You'll see that on a number of points I'm operating with a fundamentally different system of thought and hermeneutic than "divine blessing" proponents, which can make dialogue a bit less productive at times (or at least more involved, as you have to define terms every step of the way).

One final note about Deuteronomy 29. Here we see the principle of national judgment as it is primarily applied to Israel, the idea being that this judgment is only secondarily (and contrastively) applied to the nations.

The problem with thinking along these lines today, you will note, is that "the moist and the dry alike" taste the Lord's judgment... this is the sense at which the type operates BELOW the principle of faithfulness. Obedient believers (the remnant) are swept up into the judgment of the people, when the nation is disobedient to the terms of the covenant. This is not a principle we see deployed in the New Testament, because now we deal with the reality, not the shadow.

The divine blessing position leaves us preaching moralism to the nations, "relative righteousness" as a goal for governments and peoples. But that is not what God is interested in.  Thus, the conclusion of Dt. 29: “The secret things belong to the Lord our God, but the things that are revealed belong to us and to our children forever, that we may do all the words of this law." God's dealing with us in history is mysterious, but we are responsible to obey God's law, and the covenant.

“You know how we lived in the land of Egypt, and how we came through the midst of the nations through which you passed. And you have seen their detestable things, their idols of wood and stone, of silver and gold, which were among them. Beware lest there be among you a man or woman or clan or tribe whose heart is turning away today from the Lord our God to go and serve the gods of those nations. Beware lest there be among you a root bearing poisonous and bitter fruit, one who, when he hears the words of this sworn covenant, blesses himself in his heart, saying, ‘I shall be safe, though I walk in the stubbornness of my heart.’ This will lead to the sweeping away of moist and dry alike. The Lord will not be willing to forgive him, but rather the anger of the Lord and his jealousy will smoke against that man, and the curses written in this book will settle upon him, and the Lord will blot out his name from under heaven. And the Lord will single him out from all the tribes of Israel for calamity, in accordance with all the curses of the covenant written in this Book of the Law. And the next generation, your children who rise up after you, and the foreigner who comes from a far land, will say, when they see the afflictions of that land and the sicknesses with which the Lord has made it sick— the whole land burned out with brimstone and salt, nothing sown and nothing growing, where no plant can sprout, an overthrow like that of Sodom and Gomorrah, Admah, and Zeboiim, which the Lord overthrew in his anger and wrath— all the nations will say, ‘Why has the Lord done thus to this land? What caused the heat of this great anger?’ Then people will say, ‘It is because they abandoned the covenant of the Lord, the God of their fathers, which he made with them when he brought them out of the land of Egypt, and went and served other gods and worshiped them, gods whom they had not known and whom he had not allotted to them. Therefore the anger of the Lord was kindled against this land, bringing upon it all the curses written in this book, and the Lord uprooted them from their land in anger and fury and great wrath, and cast them into another land, as they are this day.’

“The secret things belong to the Lord our God, but the things that are revealed belong to us and to our children forever, that we may do all the words of this law.