Force

Although it sounds idea to have government policy nothing to do with religion, it is nevertheless an ingenuous expectation that politics should be independent from our spiritual belief. We know from history that the two are magnetic and electric forces of physics - they are all but one.

For that reason, when religious force moves fast enough, it generates a political one.

To go one step further, it is often to the advantage of a government to have highly religious citizens. Although a country always needs a well structured legal system to keep everything in order, one could not resolve every problem in the court. Although religion could not keep everything in order, it does help to keep most things in harmony.

That's a cut higher than in order.

Alas, that's not my invention. The Han emperors started to use Confucianism and Taoism for China, and I don't think I need to elaborate on the relation between Vatican and other European countries over the last 2000 years.

PS. The most recent example on the interaction between politics and religion is probably the heavy governmental support to the movie Confucius.

You may argue that strictly speaking, Confucianism is not a religion. That actually brings us to a deeper water of the concept (or domains) of god, which I hope I could elaborate later.